FOREWORD

This publication may be used by the US Army, US Navy, and US Air Force during training,exercises, and contingency operations.

FREDERICK M. FRANKS, JRGeneral, USACommanding GeneralUnited States Army Trainingand Doctrine Command

MERRILL A. MCPEAKGeneral, USAFChief of Staff

RICHARD M. DEMPSEYCaptain, CEC, USNDeputy CommanderMilitary Readiness (SEABEES)

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PREFACE

PURPOSE

This manual is a guide for engineer personnel responsible for planning, designing, and drillingwells. This manual focuses on techniques and procedures for installing wells and includes expedientmethods for digging shallow water wells, such as hand-dug wells.

SCOPE AND APPLICABILITY

Engineer personnel assigned to well-drilling teams must have a basic understanding ofgroundwater principles and well-drilling mechanics and hydraulics to successfully install wells. Awell driller enhances his skills primarily from experience in solving problems, overcoming obstaclesin the field, and learning from failures. This manual reviews common experiences well drillersencounter in the field, including well installation and completion in North Atlantic TreatyOrganization (NATO) countries.

ACKNOWLEDGMENTS

Acknowledgment is gratefully made to the organizations listed below for permitting the use ofcopyrighted material in the preparation of this manual.

Baroid Drilling Fluids, Inc.Houston, Texas

Ingersoll-Rand CompanyThe Button Bit vs. The Rock

Johnson Filtration Systems, Inc.Ground Water and Wells, 3rd Edition

Sandvik Rock Tools, Inc.Percussion Drilling Equipment Operation and Maintenance Manual

The proponent for this publication is HQ, TRADOC. Submit changes for improving this publicationon Department of the Army (DA) Form 2028 (Recommended Changes to Publications and BlankForms) and forward it to Commandant, US Army Engineer School, ATTN: ATSBTDM-P, FortLeonard Wood, MO 65473-6650.

The previsions of this publication are the subject of international agreement STANAG 2885 ENGR(Edition 2), Emergency Supply of Water in War.

Unless otherwise stated, masculine nouns and pronouns do not refer exclusively to men.

This publication contains copyrighted material.

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Part One. Basics

Chapter 1Introduction

1-1. Field Water Supply. In the theater of operations (TO), the tactical or installation commanderprovides water-support requirements to the combat service support (CSS) elements. The CSSelements’ task is to provide water. Requests for well-drilling support go through operationalchannels to corps or theater army headquarters.

Tactical and logistical personnel plan and coordinate water-support functions. They ensurethat sufficient water-production and distribution assets are available to continuously support theforces in the TO. Planners should consider the following items when locating well sites:

Tactical situation.Geographical area of operations (AO).Location of existing water sources.Size of the force being supported.Planned force-deployment rates.Dispersion of forces in a geographic area.Water-consumption rates and anticipated well capacity.Availability of transportation to move well-drilling equipmentmaterials.Logistical support and main supply routes.Availability of assets for water distribution.Time required to drill and prepare a well for production.

and well-completion

Groundwater sources are normally used to supplement surface-water sources. In aridenvironments, exploring and using groundwater can reduce the need to transport water to a desiredlocation. Groundwater may also be used when threat forces employ nuclear, biological, chemical(NBC) munitions, which could contaminate surface-water supplies in the TO.

1-2. Water Detection.

a. Responsibilities. In an undeveloped or a developed TO, terrain analysts, ground-surveyteams, and well-drilling teams identify surface-water and groundwater sources. Water detectionmay be provided for all forces in the TO with assets from the Water Detection Response Team(WDRT). See Appendix A for details on the WDRT. Engineer ground-survey teams determinewhether a groundwater source is adequate and accessible for development.

b. Procedures. Analysts use surface-water, groundwater, and existing-water-facilitiesoverlays from the worldwide Water Resources Data Base (WRDB) (Appendix A). Surface- andexisting-water-facilities water sources are identified primarily from maps and visual inspection.Groundwater sources are identfied by analyzing information from groundwater-

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resources overlays, maps, aerial imagery, terrain studies, hydrologic and geologic data, well-drillinglogs, and local-national sources. Two methods of locating groundwater are--

Method 1. WDRTs, equipped with special devices that use geophysical techniques(electrical resistivity and seismic refraction), may be deployed to locate groundwater.Method 2. Well-drilling teams may drill exploratory or test wells to detect groundwater.

The second method is accurate but time-consuming. Teams should use this method only if allother water-detection methods are unsuccessful or are not available. The methods used for detectingwater depend on the urgency for finding groundwater and the resources available. Speed andaccuracy are essential for locating water in any TO.

c. Equipment. The WDRT’s water-detection equipment can be deployed by air, sea, or groundtransport into a developed or undeveloped TO.

1-3. Well Drilling. Wells provide water to the deployed forces in an undeveloped TO, to theforward deployed units in a developed theater, and to the forces that occupy permanent orsemipermanent, freed Army installations in a developed TO. Wells are located and drilled in secureareas in an installation or in the area of operation at brigade level or higher.

a. Forward Deployed Forces in a Developed TO. Well-drilling operations support forwarddeployed forces and force buildup in a developed TO. Groundwater sources supplement, but donot replace, surface-water sources. Well-drilling teams conduct well-drilling operations during allphases of an operation. Rapid movement of the well-drilling team into the TO is not essential.Teams with organic equipment arrive at the TO primarily by sea or ground from pm-positionedlocations. The teams depend on engineer units for logistical and administrative support.Transportation support is required for movement of will-drilling equipment and components.

b. Permanent or Semipermanent Fixed Installation Forces in a Developed TO. Theseechelons-above-corps (EAC) installations are located in built-up or rural areas where water sourcesmay be available. Groundwater sources supplement existing water sources to meet installationwater requirements. The wells are permanent. The facilities engineer manages all water utilitieson an installation.

c. Combat Zone (Corps Level and Below). The Operations and Training Officer (US Army)(S3) of the engineer battalion that the well-drilling team is attached to coordinates operations withthe quartermaster unit. When the well-drilling team completes a well, they turn it , all installedequipment and technical specifications over to the S3. The S3 then turns the operation over to thequartermaster unit. The quartermaster unit is responsible for--

Drawing water from the stave tank to purify, treat, store, and distribute water.Operating all equipment at the well site, to include the well pump and generator.Maintaining all equipment except the well pump and screens.

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Any well repair or maintenance that exceeds the capability of the responsible quartermasterunit will be coordinated through the staff engineer of the corps support group or the engineer unitthat supports the area.

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d. Communications Zone (EAC). The well-drilling team’s S3 coordinated operations withquartermaster units, civil-affairs units, or host-nation support personnel. When the well-drillingteam completes a well, they turn over the operating well, all installed equipment, and the technicalspecifications to the S3, who then turns the operation over to the facilities engineer. The facilitiesengineer coordinates with the quartermaster planners, civil-affairs personnel, or the host nationregarding well operations and maintenance. Host-nation support is used whenever possible tosupport well-drilling operations.

1-4. Well-Drilling Teams.

a. Army. Army well-drilling teams have qualified personnel and equipment to drill and developwater wells and to repair wells on a limited basis. Field water supply is an Army combat servicesupport function; however, Army engineer organizations are responsible for the following water-related actions in a TO:

Surveying, identifying, and compiling data pertaining to surface-water sources tosupplement existing data.Compiling data using information, such as well-drilling logs and ground surveys, toestablish well-drilling sites for groundwater.Well drilling by teams that are organic or attached to nondivisional engineer units.Constructing and repairing rigid water-storage tanks and water pipelines, when used.Improving water-point sites requiring construction support.Constructing and maintaining permanent and semipermanent water utilities at fixedArmy installations, including water wells.

To accomplish the well-drilling mission, well-drilling teams (with organic equipment) aredeployed to the TO by air, sea, or ground. Each team has a truck- or semitrailer-mounted drillingmachine. They use these machines to reach deep aquifers and develop wells. Teams also havewell-completion kits. Kits include the casing, screen, pumps and generators, and other necessaryequipment needed to provide an aquifer-to-storage-tank capability. The teams depend on engineerunits or the facilities engineer for logistical and administrative support. Transportation support isrequired to move well-drilling equipment and components.

b. Navy. See Appendix B for information on Navy well-drilling teams and operations.

c. Air Force. See Appendix C for information on Air Force well-drilling teams and operations.

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Chapter 2Groundwater

2-1. Fundamentals. To locate and evaluate water sources, engineers must know about the earth’stopography and geologic formations. Surface sources of water, such as steams, lakes, and springs,are easy to find. Quartermaster personnel are responsible for locating surface-water sources andfor providing adequate water supplies to troops in the field. Groundwater sources often requiremore time to locate. Geologic principles can help engineers locate groundwater supplies andeliminate areas where no large groundwater supplies are present. About 97 percent of the earth’sfresh water (not counting the fresh water frozen in the polar ice caps and glaciers) is locatedunderground. Most of the groundwater tapped by water wells is derived from precipitation on theearth’s surface.

2-2. Hydrologic Cycle. The constant movement of water above, on, and below the earth’s surfaceis the hydrologic cycle (Figure 2-1, page 2-2). The concept of the hydrologic cycle is thatprecipitation returns again to the atmosphere by evaporation and transpiration. Undemanding thiscycle is basic to finding groundwater. Three-fourths of the earth’s surface is covered by oceanwater. Direct radiation from the sun causes water at the surface of the oceans to change from aliquid to a vapor (evaporation). Water vapor rises in the atmosphere and can accumulate as clouds.When the clouds accumulate enough moisture and conditions are right, the water is released in theform of rain, sleet, hail, or snow (precipitation).

a. Recharge and Discharge. Precipitation on land surfaces maybe stored on the surface. Italso flows along the surface (runoff) or seeps into the ground (infiltration). Surface storage is inlakes, ponds, rivers, and streams and is snow and ice. Polar ice caps and glaciers store 85 percentof the earth’s freshwater. Runoff provides the main source of water for streams and rivers. Waterinfiltrating into the soil is the major source of groundwater. Water that seeps into the groundrecharges groundwater resources.

As groundwater moves from the recharge area, it may discharge back to the surface.Groundwater flows from recharge areas to discharge areas where the water is discharged to lakes,rivers, springs, and oceans (Figure 2-2, page 2-2). Another form of discharge is the consumptionof water by plants and animals. Plants draw large quantities of water from the soil and return thiswater to the atmosphere (transpiration). Man also causes water discharge for consumption.

b. Water Storage. Water wells are constructed to produce water supplies from groundwaterreserves. Developing a groundwater supply has many advantages over using surface water.Groundwater is more abundant than surface water, is cleaner, requires less treatment, and may beeasier to protect than surface-water supplies. A water well is easy to seal from natural contaminationand to protect from clandestine contamination. Short-term droughts have little effect ongroundwater, which can be depended on when surface sources dry up.

2-3. Groundwater Occurrence. The hydrologic cycle exists on global and local levels. Byunderstanding the local hydrologic cycle, it is possible to predict the directions and rates ofgroundwater flow, to identify groundwater resources, and to select development areas. An areadrained by a stream or river is a drainage basin. For example, the Mississippi River Basin includes

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most of the area between the Rocky and Appalachian Mountains (Figure 2-3). Major river basinscan be subdivided into smaller basins. The Missouri and Ohio River Basins are regionalsubdivisions of the Mississippi River Basin. These subdivisions can also be divided into localdrainage basins (hydrographic basins) for each tributary (Figure 2-4, page 2-4). The boundaries of

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hydrographic basins are usually represented by mountains or hills, which restrict the flow of water,and by low areas where the water is discharged out of the basin.

The depth to groundwater may range from 10 feet to more than 1,000 feet. In most arid areas,the shallowest groundwater sources occur in recharge and discharge areas. Precipitation overmountainous areas results in a groundwater recharge at the base of the mountains into alluvialvalleys. Precipitation over a mountainous area results in higher runoff and lower groundwaterrecharge ratios on the slopes of mountainous terrain. Even though groundwater may be shallow inthese areas, the rough terrain and the rocks make mountainous areas difficult sitings for water wells.Even though mountainous areas are presumed to be recharge areas, military engineers will not drilltactical water-supply wells on mountain sides.

2-4. Geological Setting. The ability of soils and rocks to hold and transmit water varies, and thedepth to groundwater varies in different geological settings. Physical properties of soils and rocks,such as degree of consolidation, cementation, and hardness, determine drilling methods and thepotential for groundwater production. When drilling, consolidated rock is harder to penetrate butis more stable than unconsolidated rock. Well drillers usually use a down-hole air hammer onconsolidated rock with no well casing for support. Drillers must support holes in unconsolidatedrock to avoid cave-ins. Wells in unconsolidated rock frequently yield more water at a shallowerdepth than wells in consolidated rock.

a. Unconsolidated Deposits (Soil). Unconsolidated deposits--

Cover the majority of the earth’s surface.Range in thickness from a few inches to several thousand feet.

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Can underlie consolidated rocks.Consist of weathered rock particles of varying materials and sizes.Include clays, silts, sand, and gravel.May include salt deposits and fragments of shells of marine organisms.

See FM 5-410 for descriptions and detailed analyses of the engineering properties ofunconsolidated deposits.

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b. Consolidated Deposits (Rock). These rocks consist of mineral particles of different sizesand shapes. Heat and pressure or a chemical reaction has formed the rocks into a solid mass (oftencalled bedrock). Geologists classify consolidated deposits into the following three categories,depending on origin:

(1) Igneous. These rocks form when hot molten material (magma) cools or solidifies eitherinside the earth’s crust or on the earth’s surface (lava). Basalt and granite are two common igneousrocks that military well drillers encounter.

(2) Sedimentary. These rocks are composed of sediments that are converted to rock throughcompaction, cementation, or crystallization. Sedimentary rocks cover about 75 percent of theearth’s surface. Over 95 precent of these rocks are comprised of shale, sandstone, and limestone.

(3) Metamorphic. These rocks are igneous, sedimentary, or preexisting metamorphic rocksthat undergo further transformation by temperature, pressure, or chemical changes. Thetransformation usually occurs very deep in the earth’s crust, Schist and gneiss are commonmetamorphic rocks.

2-5. Groundwater Hydraulics.

a. Porosity. Soil and rock are composed of solids and voids (pores). Groundwater can fill upand flow through pores. Pores formed at the same time as the rock such as in sand, gravel, andlava tubes in basalt, are called primary openings. Pores formed after the rock was formed are calledsecondary openings. Examples are fractures in massive igneous rocks like granite and the cavesand caverns in limestone. The pore sizes vary and mayor may not be filled with water. The ratioof volume of the pore space to the total volume of the soil or rock is called porosity. Porosity isnormally expressed as a percentage (Table 2-1). Figure 2-5 (page 2-6) shows primary and secondaryopenings.

b. Permeability. The property of permeability is related to porosity. In qualitative terms,permeability is expressed as the capacity of a porous rock or soil to transmit a fluid. Largeinterconnected pore openings are associated with high permeability, while very small unconnectedpore openings are associated with low permeability. Sand and grovel with large interconnected poreopenings have high porosity and permeability. Clay tends to have high porosity, but the very smallopenings tend to inhibit the passage of water. Therefore, clay displays low permeability.

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Hydraulic conductivity is a measurement of the capacity of rock or soil to transmit water. Thehigher the hydraulic conductivity, the faster the water will flow at a given pressure (Figure 2-6).Hydraulic conductivity is related to the size and spacing of particles or groins in soils or to thenumber and size of fractures in rocks (Figure 2-7). The hydraulic conductivity of rocks and soilcan be measured by field or laboratory tests. Findings are recorded as volume of water flowing perunit area per unit of time and expressed as foot per day or centimeter per second.

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c. Specific Yield and Retention. Table 2-2 shows specific yield and retention percentages.Only a portion of the water stored in pores can be pumped out of a well. Specific retention (Sr) isthe water that cannot be pumped out of a well and is left as a film on the rock surfaces. Specificyield (Sy) is the water that can be pumped from a well and is that part of the water that would drainunder the influence of gravity (Figure 2-8). The Sr and Sy percentages compared to porosity indicatehow much water can be developed from a rock formation.

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d. Transmissivity. Although hydraulic conductivity measures the relative flow of waterthrough a subsurface material, the results may not be an accurate measurement of the yield that canbe obtained from the material. The inaccucy exists because hydraulic conductivity does notaccount for the thickness of the water-bearing unit (aquifer). For example, a well in a 100-foot-thickaquifer will produce more than a well in a 10-foot-thick aquifer provided both aquifers have thesame permeability. Hydraulic conductivity y is the water-transmitting capacity of a unit of an aquifer(see Figure 2-9, A). Transmissivity is the water-transmitting capacity of a unit prism (the saturatedthickness) of the aquifer and usually is expressed in units of gallons per day per foot of aquifer width(see Figure 2-9, B). Wells in high transmissivity areas will produce high well yields. Wells in lowtransmissivity areas will produce low well yields. Appendix D details the Electrical Logging Systemyou can use to log shallow wells in various rock formations.

e. Yield and Drawdown. Yield isthe volume of water discharged fromthe well per unit of time when water isbeing pumped or is flowing freely.Yield is commonly measured in unitsof gallons per minute (GPM) andgallons per hour (GPH) for smallyields or in cubic feet per second (cfs)for large yields. Yield is a measure ofhow readily an aquifer gives up itssupply of groundwater.

Drawdown is a measure of howmuch the water level near the well islowered when the well is pumped.Drawdown is the difference (in feet)

between the static water level and the water level when pumping (Figure 2-10, page 2-10). SeeChapter 8 for methods of measuring yield and drawdown.

f. Hydraulic Gradient. Darcy’s Law describes the flow of groundwater and is applied toevaluate aquifer and aquifer material hydraulic characteristics. The hydraulic gradient is the changein head (water elevation) with distance. The hydraulic gradient determines the direction ofgroundwater flow. To calculate the hydraulic gradient, use the following formula:

where-

i = hydraulic gradient, in feeth = hydraulic head, in feet.L = horizontal distance from h1 to h2, in feet (Figure 2-11, page 2-10)

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Darey’s experiments show that the flow of water through a column of saturated sand isproportional to the difference in the hydraulic head at the ends of the column. Darey’s Law is stillused as the basic principle that describes the flow of groundwater and is expressed as follows:

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Q = KiA

where-

Q = quantity of water discharged, in cfs.K = hydraulic conductivity (constant factor).i = hydraulic gradient, in feet.A = cross-sectional area, in square feet.

g. Aquifer Tests. Groundwater aquifer performance and well efficiency are tested by placingboreholes through the aquifer. Testing and recording the yield and the drawdown can provide usefulinformation to select the best pumping equipment and well screens for the actual well.Measurements of drawdown in observation wells (near the pumping well) and accurate pumpingrates of the actual well will provide useful information on the hydraulic characteristics of the aquifer.

Aquifer tests provide values of hydraulic conductivity and transmissivity that better representthe actual aquifer than laboratory permeability tests conducted on small intact samples. The muchgreater volume of aquifer material tested in a field aquifer test takes into account secondary porosityin fractures and connected voids as well as the primary porosity of the materials, Field aquifer testsmay also reveal the presence of boundary zones, which are zones of greater or lesser permeabilityor recharge zones that define the limits of the aquifer. Aquifer test data are useful in determiningwell yield (discharge) for groundwater supply and in engineering projects requiring dewatering ofexcavation sites and subsurface excavation. Field testing of aquifers is described in Chapter 7 andAppendix C of Technical Manual (TM) 5-818-5.

2-6. Aquifers. Saturated rock or soil units that have sufficient hydraulic conductivity to supplywater for a well or spring are aquifers. Aquifers transmit water from recharge areas to dischargeareas, such as springs, lakes, and rivers. Typical aquifers are gravel, sand, sandstone, limestone,and fractured igneous and metamorphic rock. Those subsurface rock or soil units that do nottransmit water readily and cannot be used as sources of water supplies are called aquicludes. Typicalaquicludes are clay, shale, and unfractured igneous and metamorphic rock. Aquicludes that existbetween aquifers are confining beds; the water moves only within the aquifers.

a. Unconfined. These are aquifers that are partly filled with water, have fluctuating waterlevels, and can receive direct recharge from percolating surface water. Wells drilled into anunconfined aquifer are called water-table wells (Figure 2-12, page 2-12).

b. Confined. These are aquifers that are completely filled with water and are overlaid by aconfining bed. The water level in a well supplied by a confined aquifer will stand at some heightabove the top of the aquifer. Water that flows out of the well is called flowing artesian (Figure 2-13,page 2-1 2). Water rises because of the pressure that the overlying materials exert on the water andthe height of the column of water driving the water through the interconnecting pores of the aquifer.The height of the column of water that is driving water through the aquifer is the head. The heightthat the water will rise to inside a tightly cased artesian well is the potentiometric surface andrepresents the total head of the aquifer.

c. Perched. These aquifers lie above an unconfined aquifer and are separated from thesurrounding groundwater table by a confining layer (Figure 2-14, page 2-13). The aquifers areformed by trapping infiltrating water above the confining layer and are limited in extent and

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development. In some arid environments, perched aquifers form sources of shallow and easilydeveloped groundwater.

d. Catchment. This is formed where impervious rock underlies a zone of fractured rock oralluvium that serves as a reservoir for infiltrated water (Figure 2-15). A catchment can be a special

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type of perched aquifer. Catchments cannot provide large quantities of water, but they may provideeasily developed groundwater for small demands or temporary supplies for drilling operations.

e. Material.

(1) Soil. These aquifers occur in unconsolidated deposits. Examples of sediment deposits andtheir sources are--

Alluvium, which comes from running water.Glacial drift, which comes from flowing ice.Sand dunes, which come from blowing winds.

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Sand and gravel deposits are the primary materials of unconsolidated aquifers. Alluvialdeposits are prevalent in river valleys in humid environments and in dry wadis in arid environments.In many desert areas, alluvial deposits may be the primary source of groundwater. These depositsmay be unconfined, confined, or perched.

(2) Rock. This aquifer is a mass of rock that can store and transmit groundwater.

(a) Limestone and dolomites. These are carbonate rocks that dissolve when carbon dioxidefrom the atmosphere and groundwater mix to form carbonic acid. The acid dissolves and widensthe fractures and bedding planes into larger rock openings. These openings may eventually developinto caves. Limestone with fractured zones develop solution channels. Caves can be productiveaquifers that yield appreciable quantities of groundwater (Figure 2-16).

(b) Basalt. This is an igneous rock and can be a very productive water bearer. The waterflows through openings that include lava tubes, shrinkage cracks, joints, and broken or brecciatedzones at the top of cooled lava flows (Figure 2- 17).

(c) Sandstone. This is consolidated or cemented sand. In unfractured sandstone, groundwatercan be stored in the pores between individual sand grains and can be recovered through pumping.Water in sandstone may flow through bedding planes and joints.

2-7. Groundwater Exploration. In groundwater exploration, it is possible to preedict the locationof an unconfined aquifer within alluvial sediments. However, identifying these unconfined alluvialaquifers requires a detailed knowledge of sediments in the area. Usually, this information can only

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be obtained from existing water- or oil-well-drilling records or from an exploratory drilling program.For development of water supplies in support of tactical operations, the unconfined aquifer will bethe preferable target zone. Deeper confined aquifers should be investigated if an unconfined aquifercannot provide an adequate water supply or if the unconfined aquifer is contaminated.

Rock aquifers should be considered for exploration only when soil aquifers are not present orwhen soil aquifers cannot provide a sufficient water supply. Identifying suitable well sites in rock

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aquifers is more difficult than in soil aquifers. Water development in rock aquifers is more time-consuming and costly and has a higher risk factor. However, in some areas, rock aquifers may bethe only source of groundwater.

Indicators of groundwater resources are those conditions or characteristics that indicate theoccurrence of groundwater. No indicator is 100 percent reliable for detecting groundwater, but thepresence or absence of certain indicators can be used as detection possibilities. Indicators useful inidentifying groundwater resources are called hydrogeologic indicators (Table 2-3).

a. Reservoir Indicators. These indicators are characteristics in soils, rocks, and landforms thatdefine the ability of the area to store and transmit groundwater but do not directly indicate thepresence of groundwater. One of the first steps in groundwater exploration is to identify andevaluate reservoir indicators.

The size, shape, and water-bearing characteristics of a hydragraphic basin are important inevaluating water resources. The characteristics could be more useful in selecting sites for ground-level study or drilling than knowing the indicators that indicate the presence of groundwater. Plantsaround a dry lake bed are good indicators of groundwater. However, dry lake beds contain veryfine-grained sediments; wells in these areas usually produce low water yields and contain poorquality groundwater. The rock or soil type present could be the most important reservoir indicatoras it usually defines the type of aquifer and its water-producing characteristics. For reconnaissance,it is only necessary to recognize three types of rock and one type of soil.

(1) Igneous Rocks. These are poor aquifers except where the rocks have been disturbed byfaulting or fracturing (Table 2-4). In many cases, the rocks are not capable of storing or transmittinggroundwater and will act as a barrier to groundwater flow. In other cases, the stresses andmovements of mountain building may have resulted in fracturing of the rock. groundwater canaccumulate in fractures and move through the rock if the fractures are connected. Mostgroundwater-bearing fractures are within 500 feet of the surface, and drilling deeper to find waterin igneous rocks is not advised. Wells in these aquifer are often poor producers and are seldomdeveloped unless no other water source is available.

(2) Metamorphic Rocks. These areas rarely produce sufficient groundwaterand are consideredan effective barrier to groundwater flow (Table 2-4). Metamorphic rocks have poor potential forgroundwater development.

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(3) Sedimentary Rocks. These areas have the greatest potential for groundwater development(Table 2-4). Sedimentary rocks are capable of supplying low yields if unfractured and moderate tohigh well yields if fractured. Sandstone, limestone, shale, and evaporites are the four common typesof sedimentary rocks.

(a) Sandstone. Sandstone’s ability to stem and tramsmit groundwater varies. If the sand grainsare small and tightly cemented together, a well will have a low yield, but if the rock has been fracturedextensively, a well could have a high yield. If the sand grains are relatively large and poorlycemented, moderate to high well yields may be possible.

(b) Limestone and dolomites. Undisturbed limestone and dolomites are poor aquifers butlimestone can bean excellent water source, where fractured. In some areas of the world, limestoneareas are the principal groundwater sources. Fractures in limestone are more important than in otherfractured rocks because when groundwatermoves through the fractures, it can dissolve the rock andenlarge the fractures. This process is called dissolution. Dissolution allows the rock to store andtramsrnit greater volumes of water than other types of fractured rocks. In most cases, limestone hasbeen fractured and is considered the highest potential source of groundwater from rock.

(c) Shale. Shale is fine-grained, does not usually store much groundwater, and does nottransmit large quantities of groundwater. Where fractured, shale generally can only produce a fewgallons per minute. However, identifying shale units is important because shales could indicate thatartesian conditions exist in more productive water-bearing units below or between shale layers.

(d) Evaporites. Evaporites are generally capable of storing and transmitting groundwater buttend to dissolve in the water. Groundwater from evaporites is often unfit for human consumptionand often not fit for any use. Because of the poor water quality, evaporites are generally consideredto have poor potential for development. Because evaporites can dissolve in the water during drilling,immediate surface areas could collapse and men and equipment could be lost. Special protectivemeasures must be taken when developing a well in evaporites.

(4) Alluvium. groundwater is most readily available in areas under soils (unconsolidatedsediments). This is largely because uncemented or slightly cemented and compacted materials havemaximum pore space, are relatively shallow, and are easily penetrated. Soils deposited by running

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water are called alluvium. Alluvium has been formed in relatively recent geologic time and isgenerally restricted to lowland terrain features, such as alluvial valleys, terraces along rivers, alluvialfans, glacial outwash plains, and alluvial basins and between mountains and coastal terraces. Factorsthat have an important bearing on groundwater yield in soils are particle size, cleanliness (percentof frees), and degree of sorting or gradation. Clay yields almost no water, silt yields some, but veryslowly. A well-sorted, clean, coarse sand or gravel yields water freely.

(a) Valleys. Alluvial valleys are one of the most productive terrains for recoveringgroundwater (Figure 2-18). Normally, sand and gravel form a large part of the stream alluvium sothat wells located in the alluvium are likely to tap a good aquifer or series of aquifers Individualaquifers do not usually extend far, and the number and depth of water-bearing sands and grovelschange rapidly from place to place.

Alluvium tends to become progressively finer downstream as the stream gradient decreasesand the distance from outcrops of rock increases. In lower stream courses far from had-reckhighlands, alluvium is mostly silt and clay, with a few sand stringers. A shallow well has a smallchance of striking such a sand stringer. The sands may be so fine-grained that most wells will havesmall or moderate yields. For large supplies, several wells or deeper wells may be needed.

(b) Stream and coastal terraces. Stream and coastal terraces usually are underlaid by grovelor sand deposits similar to floodplain alluvium. If the terraces are fairly bread and the depositsthick, they may be good water sources (Figure 2- 19). In someplace, terraces are so deeply trenched

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by stream erosion that most of the groundwater rapidly drains out of the terrace gravels through thestream-cut slopes. Well drillers must be swam of the possibility of saltwater intrusion problemswhen drilling in coastal areas.

(c) Fans. Alluvial fans can be found where steep mountain slopes rise abruptly from adjacentplains (Figure 2-20, page 2-20). The stream coming from the mountains drop coarse material nearthe apex of the fan and progressively freer material down the slope. At the toe of a large fan, thedeposits are mostly silt and clay, with few sand stringers. Alluvial fans often produce groundwaterthe water depth is greater than the depth in alluvial valleys. The aquifers often have a braided patternand individual beds are limited in extent. aquifers are abundant near mountains. However, to reachwater may require drilling several hundred feet. Large boulders, which are common at the apex ofthe fan, can make drilling difflcult. Down the slope of a fan, aquifers get progressively thinner(pinch out). In the lower part of a large fan, test drilling may be needed to locate a productive bed.

(d) Basins. Alluvial basins are in regions where mountains alternate with structural troughs(Figure 2-21, page 2-20). Erosional products from the mountains partly fill the basins with alluviumlaid down as a series of coalescing alluvial fans. The upper alluvial slopes form piedmont plainsor alluvial aprons that gradually decrease in slope toward the interior of the basin until they mergewith the interior flats. Lakes or playas occupying part of the central flat are usually saline. Lake-bottom deposits are largely clay. Many alluvial basins are good sources of groundwater. Goodwells yield several hunched to a thousand or more GPM.

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(e) Glaciated regions. Glaciated and postglaciated areas can yield water from glacial deposits(Figure 2-22). Large quantities of alluvium laid down by steams emerging from glaciers (glacialoutwash) contain a higher percentage of gravel and coarse sand than clay contains. Such areas aregood sources of groundwater. Extensive deposits occur in all glaciated regions of the earth,especially in the northern United States, northern Europe, and areas bordering high mountains.Many large cities, including some in the upper Mississippi basin, get their water from glacialoutwash sediments. Glacial materials deposited directly by ice (glacial till) are poor water bearers,yielding barely enough for farm wells. In places where outwash sands and gravels are interbeddedor associated with the till, good aquifers form. Some of these aquifers may carry water underpressure.

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(5) Stratigraphic Sequence. The stratigraphic sequence of geologic strata that occurs in an areacan give clues to the types and depths of aquifers present. Figure 2-23 shows a stratigraphic columnfor a portion of the arid Great Basin. The Great Basin contains a number of individual rock units.Some of these units, such as the Ely Limestone, can readily transmit water, but other units, such asthe Eureka Quartzite, are relatively impermeable and cannot store or transmit exploitable quantitiesof groundwater. Relatively impermeable units are aquitards or aquicludes. Aquitards are units thatretard or slow the passage of water.

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In the stratigraphic sequence, there are five discrete aquifers and six discrete aquitards. Byknowing the stratigraphic sequences in a region, it is possible to predict the type of aquifer presentat a given depth, For example, the Ely Springs Dolomite is not highly fractured, but the dolomiteis a productive aquifer where it is fractured. Because this unit is not overlain in the area by anaquitard, it could be an unconfined aquifer. The stratigraphic sequence indicates that the EurekaQuartzite underlies the aquifers and is an impermeable barrier or aquitard. This unit is underlainby the Pogonip Group that could provide suitable quantities of groundwater. Because this unit isoverlain and underlain by aquitards, it is a confined aquifer. By using the geologic map, it is possibleto estimate the thickness of each unit and the anticipated well depth. If data exists for this aquiferin other areas, it may also be possible to predict the expected well yield and groundwater quality.

In soils, the stratigraphic sequence is usually less extensive, more variable, and not as wellknown as rock. Alluvial deposits often consist of interbedded gravel, sand, silt, clay, mixtures ofthese materials, and, possibly, interbedded evaporite deposits. These sediments often occur incomplex stratigraphic sequences with some units discontinuous and other units grading intodifferent soil types vertically and horizontally. Unless sufficient existing well data is available, itis impractical to define the stratigraphic sequence of such sediments.

(6) Structure Density and Orientation. Geologic structures, such as folds, fractures, joints, andfaults, are features that disrupt the continuity of rock units. For groundwater exploration, identifyingfolds has a limited use but identifying faults and fractures is important, especially in rock aquifers.The ability of rock aquifers to transmit groundwater is related to the number and size of fracturesin the rock. Density of fractures is an important consideration in locating well sites in rock terrain.Figure 2-24 shows a structure map of part of western Iran. The best potential well sites are locatedat the intersection of fracture zones. Secondary sites are along individual fracture zones. Areaswith no fractures are probably low permeability-areas and poor sites for water wells.

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Fracture orientation is an important characteristic of rock aquifers and of soil aquifers Faultsmay act as either barriers to or conduits for groundwater flow. To distinguish between fault conduitsand fault barriers, vegetative indicators are important. If a fault zone is acting as a barrier togroundwater flow, groundwater accumulates behind the barrier and often becomes shallow enoughto support springs or dense stands of vegetation, or it forms wetlands (Figure 2-25).

(7) Dissolution Potential. Dissolution potential is the potential for the development of highsecondary permeability yin a soluble rock because of the dissolution of the rock through contact withgroundwater. Unfractured soluble rocks, such as limestone, have a low permeability referred to asthe primary permeability of the reck. Where fractured, the rock has a secondary permeability thatis related to the size and density of the fractures. If the rock is soluble and saturated, the contactbetween the groundwater stored or moving through the fractures and the rock may result indissolution of the rock.

The dissolution process increases the size of fractures and can result in an increased secondarypermeability. Many of the world’s caves and sinkholes (karst topography) result from limestonedissolving in groundwater and are indicators of high dissolution potential. However, if such featuresare not present, dissolution potential must be estimated on the basis of rock type and structuredensity. The highest dissolution potential occurs in heavily fractured carbonates (limestone anddolomite) and evaporites. Other rock types generally do not dissolve in groundwater and identifyingdissolution potential is of little use.

(8) Grain Size and Sorting. The grain size and sorting of an aquifer are related to the porosityand permeability of the aquifer and the production capability of the aquifer. Fine-grained materials(clay) have a high porosity but a very low permeability and are poor aquifers. Sands have porosity(about half that of clay) and high permeability and are usually productive aquifers. Generally, wellproduction capacity is directly promotional to grain size. Areas of fine-grained sediments (playasand lake beds) have poor water-production potential. Areas of coarse-grained sediments (alluvialfans) have a higher potential.

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(9) Lithification. This is the process by which sediments are converted to rock. Lithificationincludes compaction, consolidation, cementation, and desiccation. The degree of compaction orconsolidation affects the porosity and permeability of an aquifer (Figure 2-26). Porosity andpermeability of unconsolidated materials (subjected to little or no overburden pressure) are relatedto grain size. With compaction and consolidation, the pore spaces between grains are reduced andthe porosity and permeability of the aquifer are decreased.

Another source of lithification is the cementing of groins by the precipitation of minerals fromsolution in the groundwater. Many fragmented sedimentary rocks are cemented by silica or calciumcarbonate precipitation from the waters they are deposited in or from waters introduced after theyare deposited. Cementation often occurs along fault zones where deep mineral-rich water migratesupward. When the minerals and water mix, they precipitate travertine or other minerals along thefault zone. This can result in barriers to groundwater flow in areas selected as potential well siteson the basis of the fault zones.

(10) Drainage Basin Size. Because most groundwater is derived from the infiltration ofprecipitation over an area, the size of individual drainage basins can help define the overallgroundwater potential. Large drainage basins may receive more precipitation and have a largergroundwater supply than smaller basins. This is true where precipitation is the same over a region;however, it may not apply in areas of high relief or variable climate.

Perhaps the most useful areas where drainage basin size can give an indication of groundwaterpotential is in mountainous terrain near coastal areas. In such areas, the larger drainage basinsreceive more recharge from precipitation. This recharge flows toward the coast and the areas ofhighest groundwater potential occur along the coastal plains adjacent to the larger basins. In aridenvironments, recharge usually coincides with areas where surface water drains from themountainous areas and infiltrates into the groundwater system. The magnitude of this infiltrationusually depends on drainage basin size and on the groundwater resource potential of the area.

(11) Landforms. Identifying landforms with drainage patterns can help identify rock types inareas without geologic maps. Landforms can provide information related to water depth, well-production potential, and water quality. Table 2-5 lists landform classifications with hydrogeologicconditions that may be based on the presence of the landforms.

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(12) Elevation and Relief. Elevation and relief provide an idea of the amount of groundwaterreplenishment within a drainage basin and its groundwater potential. In a region of about the samelatitude, precipitation distribution is related to the elevation of the area with zones of higher elevationreceiving more precipitation than lower areas. A small drainage basin at a high elevation mayreceive appreciably more recharge from precipitation than a much larger basin at a lower elevation.Relief also has some effect on groundwater recharge. Areas with high relief (valleys bounded byprominent mountain ranges) have well-defined and easily identifiable recharge areas. In broadplains or plateaus, the moderate relief does not indicate recharge areas, and other indicators (grainsize or drainage density) must be used.

(13) Drainage Pattern and Density. Recognizing drainage patterns can help define rock types,recharge areas and potential, and general hydrologic conditions of an area. Without geologic mapsor other information on rock types, classification of the drainage pattern and landforms can providean accurate interpretation of rock types and recognition of the area’s structure. Because mostgroundwater recharge occurs as infiltration of surface-water drainages, areas with high drainagedensities receive more recharge than areas with low drainage densities. Recognizing drainagepatterns and density can provide indications of the type of aquifers the magnitude of recharge inan area, and directions of groundwater flow. Figure 2-27 (page 2-26) shows some of the morecommon drainage patterns. Rock has widely spaced rectangular or dendritic patterns and alluviumhas medium to widely spaced parallel drainage patterns along alluvial fans and dendritic patternsalong valley ares and floodplains.

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b. Boundary Indicators. These are characteristics that are indicative of local or regionalgroundwater flow systems. By identifying the boundaries of flow systems, it is possible to definedirections of groundwater flow and to estimate the depth and quality of groundwater within an area.Boundary indicators do not directly indicate the presence of groundwater in an area.

(1) Recharge Areas. These are areas where the groundwater reservoir is replenished. Rechargemay be derived from the runoff of precipitation into rock fractures in mountainous areas, leakagealong streambeds or under lakes, or the flow of groundwater from upgradient areas. Figure 2-28shows a sketch map of a hydragraphic basin with identified recharge areas. Some recharge occursin mountain areas as direct infiltration. The precipitation that does not infiltrate runs off into thelocal drainage network. Some recharge occurs along the streambeds and the remaining runoffdischarges on the alluvial fans where it infiltrates. Precipitation over the valley floor is channeled,and quantities of recharge occur along the valley drainage system. Various amounts of rechargeare derived from lakes, ponds, or channels that may occur within the basin.

The recharge of groundwater from surface water sources usually results in a mound (bulge) inthe surface of the groundwater (Figure 2-29). Groundwater in such areas flows away from therecharge sources. If the source is a lake, flow is radial away from the source. If the source is alinear source (mountain range or a stream), the groundwater divides and flow is primarily in twodirections from the source. Areas recharged by direct infiltration or precipitation usually contain

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good quality groundwater.Groundwater under lakes may exhibitpoor water quality becauseevaporation of lake water mayincrease the concentration ofchemicals in the lake and any rechargederived from the lake. Groundwaterrecharged from streams is usuallyintermediate quality betweengroundwater recharged byprecipitation and lakes.

Subsurface recharge fromadjacent basins is often difficult toassess. By knowing the elevation ofgroundwater in adjacent areas, thetransmissivity of the aquifer, and thewidth of the recharge area, it ispossible to estimate the amount ofrecharge from subsurface flow. Thisestimate usually is not possible inareas with limited data. It is possibleto infer that such flow is occurring onthe basis of differences in elevationand the location of barriers or conduitsbetween hydrographic basins.

(2) Discharge Areas. Recharge to and discharge from a hydrographic basin must be equal.Figure 2-30 (page 2-28) shows a sketch map of a hydrographic basin with identified discharge areas.Figure 2-31 (page 2-28) shows the directions of groundwater flow from the recharge to the discharge

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areas. groundwater discharge canoccur in streams and lakes throughconsumption by plants or man andby subsurface flow to adjacent downgradient basins.

The location of discharge areascan help identify areas of shallowgroundwater. Streams sustained bygroundwater seepage, wetlands, andcertain types of vegetation indicatedischarge areas where groundwateris close to land surface. Some typesof vegetation are capable of sendingtap roots to depths of over 100 feetand are not indicative of shallowgroundwater. The location ofsubsurface discharge areas requiresmore detailed knowledge of thehydrologic balance of the area.

(3) Impermeable andSemipermeable Barriers. Thequantity and rate of groundwaterflow from recharge areas todischarge areas are controlled by thetransmissivity of the aquifers.Impermeable barriers are thosefeatures (solid rock masses) throughwhich groundwater cannot flow.Semipermeable barriers are thosefeatures (faults or fractured rockmasses) that restrict flow but do notact as a complete barrier. Suchfeatures should be recognizedbecause they usually form theboundaries of groundwater flowsystems and, when located within aflow system, can result in areas ofshallow groundwater.

(4) Surface-Water Divides. Surface-water divides can form boundaries between groundwaterflow systems. The mounding of groundwater under areas that receive recharge from the infiltrationof precipitation causes groundwater to flow away from the recharge area. Similarly, surface waterflows away from topographic highs that often correlate with groundwater recharge areas so thatsurface-water flow patterns usually coincide with groundwater flow patterns. The identification ofsurface-water divides can help define groundwater flow systems.

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c. Surface Indicators. Surface indicators are those features that suggest the presence ofgroundwater. These indicators can provide information about the depth, quantity, and quality ofthe groundwater resoures in an area; however, they do not positively indicate the presence ofgroundwater. The resource potential of an area is an inference on the basis of the presence (orabsence) of certain indicators and particularly the association of these indicators.

(1) Springs. Springs are effluences of groundwater occurring where the water table interceptsthe ground surface. Springs are usually good indicators of the presence of shallow groundwateroccurrences. However, the presence of shallow groundwater may not be indicative of a good areafor well construction. Springs occur where groundwater discharges to the earth’s surface. Figure2-32 shows several types of springs. Faults, valley-depressions, and alluvial-fan springs maydischarge appreciable quantities of groundwater.

(2) Vegetation Type. Certain types of vegetation (or vegetative assemblages) are associatedwith specific hydrogeologic environments. Some plants (phreatophytes) can only exist if their rootsystems are in direct contact with groundwater. Phreatophytes, such as mesquite tress, have taproots that go down more than 100 feet. Shrubs, such as saltbush, have roots that descend only afew feet, making them excellent indicators of shallow groundwater. Table 2-6 (page 2-30) listsseveral plants that indicate the presence of shallow groundwater. The density of vegetation can help

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define the location of recharge and discharge areas. Dense stands of vegetation along streamchannels are riparian vegetation. Riparian vegetation along streams that discharge mountainouswatersheds indicates that surface water is infiltrating the streambed and recharging the groundwater.In many cases, the vegetation will decrease in density after the stream reaches the valley floor.Somewhere along the sterambed, the riparian vegetation assemblage will give way to the typicalvalley-floor vegetation.

(3) Playas. These are dry lake beds composed mainly of clay and located in intermountainvalleys (Figure 2-33). During rainy seasons, playas may store large quantities of surface water.

(4) Wetlands. Wetlands such as marshes, bogs, and swamps are indicative of very shallowgroundwater. Although wetlands are not typical of arid environments, they have been observed inarid flow systems where groundwater accumulates behind flow barriers. Wetlands can also occurin low-lying areas where the discharge of regional spring water accumulates. The presence ofwetlands is an excellent indicator of groundwater. However, wetlands generally are not suitablefor water-well locations because of low permeability of wetland soils, marginal water quality from

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the evapotranspiration processes of wetland vegetation, and severe mobility constraints. Wetlandsare important in groundwater detection because they usually represent regional discharge points.Areas upgradient of wetlands are usually favorable targets for groundwater development.

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(5) Streams and Rivers. Streams and rivers (including dry streambeds and riverbeds) areusually recharge areas in arid regions and may be recharge or discharge areas in temperate climates,depending on seasonal rainfall. This type of recharge is especially true of major streams that drainthe central portions of most valleys. Because recharge occurs along stream courses and streamsoccur in lower elevation areas in the valley, the areas adjacent to streams are considered goodlocations for wells, especially near the intersection of major streams. However, such locations arenot always the best available areas for water wells.

Streams often migrate over large areas of the valley floor and deposit mixtures of gravel, sand,silt, and clay. Often these deposits are discontinuous and result in a vertical sequence of poorlysorted materials with low overall permeability and low to moderate well yields. Older, buried streamchannels may be better aquifers because they are composed of coarser subgrade materials and muchof the surface contamination has been filtered out.

(6) Snow-Melt Patterns. Snow-melt patterns can provide evidence of recharge areas anddirections of groundwater flow. Snow packed in mountainous areas is usually a good source ofrecharge because slowly melting snow produces more infiltration than rainfall.

(7) Karst Topography. Karst topography results from the dissolution of carbonate rocks bygroundwater and is characterized by caves, sinkholes, closed depressions, and disappearing streams(Figure 2-16, page 2-14). These features indicate that the rock has a very high dissolution potentialand that groundwater is present. Collapse-type sinkholes (irregular, debris-filled sinkholes) usuallyindicate the presence of shallow groundwater because they result from the collapse of the surfacematerials into a dissolution cave. In some cases, the water provides evidence of the depth togroundwater.

(8) Soil Moisture. Soil moisture content can provide some indication of recharge and dischargeareas. Areas with high soil moisture are not necessarily areas with high groundwater potential andgood water-well locations. Soil moisture content is related to local rainfall and to groin size. Thesmaller the grain size, the higher the soil moisture. Playas and lake deposits often exhibit high soilmoisture but very poor groundwater potential, resulting in low well yields.

(9) Salt Encrustation. Salt encrustations often occur in playas and are indicative of salinegroundwater (Figure 2-33, page 2-31). Often, salt buildups result from the evaporation of surfacewater and can cover many acres. Certain salt-tolerant plants may grow in such areas, indicatingshallow groundwater containing high concentrations of sodium, potassium, and other soluable salts.Although salt encrustations indicate shallow groundwater, drilling for groundwater should beavoided even if water treatment equipment is available. Surface salt deposits usually indicate deepevaporite deposits. Subsurface evaporite deposits are very susceptible to collapse and should beavoided.

(10) Wells. One of the best indicators of groundwater is groundwater development with wellsystems. Water wells are difficult to detect, especially from imagery. It is possible to detect wellsindirectly from irrigation patterns. Pivot irrigation patterns (Figure 2-34) are distinctive and areusually supplied by centrally located water-supply wells. Such features are good indications thatquality groundwater is present at economic pumping depths.

(11) Reservoirs and Lakes. Surface water bodies can be groundwater recharge, discharge, orboth artificial surface-water reservoirs usually capture surface water and represent areas of

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recharge, as do natural reservoirscreated by the damming ofstreams. Natural reservoirs inlowland areas are often formed bythe discharge of groundwater fromseeps along the lake bed or fromsprings.

(12) Crop Irrigation. Cropirrigation indicates the use ofsurface or groundwater foragriculture. In most aridenvironments, surface-water-based irrigation is located adjacentto streams and rivers. Beyond theriver floodplains, agriculture isnegligible. Agriculturaldevelopment in areas withoutsurface water is a good indicator ofthe presence of groundwater atrelatively shallow depths. The leaching action of irrigated water and the use of chemical fertilizersmay impair the groundwater quality in such areas.

(13) Population Distribution. Population distribution in arid regions or sparsely populatedareas is closely related to water availability. Because of the lack of resources and technicalcapabilities for wide-scale groundwater development projects, population centers in aridenvironments without surface water are usually good indicators of groundwater supplies. Thesecenters are often located on perched aquifers with limited capabilities; the population sizes aredireectly proportional to the production capacities of the aquifers.

2-8. Desert Environments. For contingency, water-well drillers must become familiar withdrilling operations in an arid or desert environment. An arid environment usually has less than 300millimeters (mm) of rainfall per year and high average daily temperatures. Most of the soils arecoarse-grained with high porosity and permeability. Because of low rainfall, only deep water tablesmay exist. Therefore, any well-drilling units and equipment or kits deployed to a desert AO shouldbe capable of achieving maximum depth of 1,500 feet.

Generally, the more arid the region, the greater the controls the host nation will place on well-drilling activities because of the potential impact of drilled wells depleting scarce aquifers. Thehost nation may also require more detailed documentation on the water sources. Because of theamount of water consumed during desert operations (up to 20 gallons daily per person), the challengemay not be in locating and drilling for water, but in finding who can identify water sources and givepermission for using the sources.

In desert mountain areas, wells should be sited on the alluvial fans that extend from themountains to the desert (Figure 2-35, page 2-34). Mountain areas usually receive more rainfall, andthe streams draining away from the mountains carry coarse gravels and sands that, when deposited,produce the fans (Figure 2-36, page 2-34). At moderate depths, these fans may yield water. In

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deserts such as in Egypt, Jordan, and Saudi Arabia, deep confined aquifers are capable of producingextensive quantities of water. Locally, shallow confined aquifers come to the surface at an oasis,characterized by more extensive vegetation than the surrounding areas (Figure 2-37). Wells maybe sited in the vicinity of an oasis to tap the confined aquifer.

Qanats are good indicators of groundwater in some desert areas like Iran. A qanat is a man-made, gently inclined underground channel that allows groundwater to flow from alluvial gravelsat the base of hills to a dry lowland (Figure 2-38). In effect, qanats are horizontal wells. On aerialphotographs, qanats appear as a series of ant-mound- like openings that run in a straight line and actas air shafts for the channel. They may be found in arid regions of Southwest Asia and North Mica.Qanats may be up to 30 kilometers in length.

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2-9. Water Quality. Most water is run through reverse osmosis water purification units (ROWPU)before it is used, so the effect of contamination is minimal.

a. Aquifer Contamination. Military engineers must be aware of possible aquifercontamination. As groundwater is transmitted from recharge to discharge areas, it contacts soilsand rocks of the earth’s crust. Contact causes some dissolution of soil and rocks into the water andalters the chemistry of the groundwater. Discharge areas that appear to be good well sites becauseof shallow groundwater may have poor water quality and may be poor sites for groundwaterdevelopment. Discharge areas often correspond to zones of poor water quality. Generally, thelonger the distance between the recharge and discharge areas, the poorer the water quality at thedischarge area. The water-quality reduction is from the contact between the groundwater and the

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aquifer material during flow. Water consumption by plants often results in decreased water qualityby the concentration of soluble salts in the groundwater.

In very shallow groundwater (less than 10 feet below land surface), water quality can bedecreased by direct evaporation of water from the soil. Vegetation type can be used to infergroundwater quality characteristics. Saltbush around playas indicates not only the presence ofshallow groundwater but also the probable occurrence of saline water, which would requiretreatment. The high evaporation rate in arid environments concentrates chemicals in the water,resulting in brackish or saline water quality.

b. Saltwater Intrusion. Saltwater intrusion into fresh groundwater is a problem in coastal areasand on islands. Saltwater is unfit for most human use and is harmful to automotive cooling systems,boilers, and other types of machinery. Chemical analysis determines the accuracy of contaminationand salt levels. The average concentration of dissolved solids in sea water is about 35,000 parts permillion (ppm) (3.5 percent). Most salts are chlorides.

When salt water and fresh water are present in sediments, fresh water floats on salt water.Contact between the two is determined by the head of the fresh water above sea level and by therelatively greater specific gravity of the salt water. The average specific gravity of sea water isabout 1.025 (taking pure water as 1.000). For every foot of fresh water above sea level about 40feet of freshwater is below sea level in homogeneous soils. The condition is best exhibited by smallislands and peninsulas composed of permeable sands surrounded and underlain by salt water (Figure2-39). The head of fresh water and resistance of the pores in sand prevents saltwater from enteringthe middle zone and mixing with fresh water. The diffusion zone (contact) between fresh water andsalt water is narrow (less than 100 feet wide) unless affected by heavy pumping.

The amount of freshwater that can be pumped without intrusion of salt water depends on localconditions, type of well, rate of pumping, and the rate of recharge by fresh water. Any decrease inthe head of fresh water by pumping or decrease in rainfall raises the saltwater level (Figure 2-40).The cone of depression (drawdown) produced in the freshwater level around a well allows acorresponding rise in the underlying salt water. Pumping a well should be restricted because salt

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water will enter the well if drawdown is maintained substantially below sea level for extendedperiods. The pumping rate should not exceed the rate of recharge. Saltwater intrusion is a potentialproblem when drilling in coastal-plain environments. Salt water may move into zones previouslyoccupied by fresh water, this is called saltwater encroachment. The fresh water and the salt watermigrate toward the well screen until a new balance between the waters is established (Figure 2-41).

c. Groundwater Contamination. Possible aquifer contamination from human activities shouldbe considered when evaluating potential supplies of groundwater. Waste products are sources ofgroundwater contamination in some areas. Sources of waste products include agricultural activities;domestic, municipal, and industrial waste disposal operations; mine spoil piles and tailings; and

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animal feedlots. Figure 2-42 shows how waste contamination enters the groundwater. Nonwastepollutants include leaks from buried pipelines, highway deicing (salting), pesticide and herbicideapplications, and accidental spills from surface transportation and manufacturing activities.Supplemental information on WRDB overlays often indicate the severity of man-induced pollution.Especially important are aspects of bacterial contamination that will preclude the use of thegroundwaters prevalent in many developing countries. Well drillers should consider the properlocation of water wells shown in Table 2-7.

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Chapter 3 Field Operations

3-1. Team Concept

a. Commander. Well-drilling teams deploy to the field to construct water wells. These teamsnormally deploy with the organic equipment they use to drill and complete the well. Teams aremanned for continuous operations and consist of two complete drilling crews, a mechanic, and adetachment commander. The detachment commander is usually responsible for--

Training and care of team members.Care and maintenance of team’s organic equipment.Support coordination with the supporting engineer unit.Deploying the team.Laying out the drilling site.Developing safety guidelines for the well-drilling team.

b. Driller. A drill team, which consists of a driller and two helpers, operates the drilling rig.A driller’s responsibilities include--

Operating and controlling the drilling rig.Establishing (and modifying when necessary) the drilling rate.Ensuring a proper mud mixture and sufficient volume.Sampling and monitoring the drill cuttings.Maintaining a driller’s log of the well.Preventing accidents around the drilling rig.

c. Helper. A helper is responsible for--

Making drill rod connections.Ensuring an adequate mud mixture during drilling.Maintaining and caring for the rig, tender, and tools during the drilling operation.

3-2. Team Planning, Coordination, and Preparation. A well-drilling team’s primaryresponsibility in planning and preparing for a drilling operation is to maintain a state of readiness.They must train, practice, and discuss operations continuously. They should study informationabout specific sites and determine alternate solutions to potential problems. Periodically, teamsshould check each component of the well-drilling equipment. Team members must maintaindrilling rigs and tender trucks in good operating condition. Before leaving for the mission area,teams should inventory all tools, parts, drilling accessories, and supplies.

Planning requirements to support Army well-drilling teams are similar to those needed for anyaugmentation team. Well-drilling teams do not have an organic headquarter. Well-drilling teamsshould be deployed and employed by an engineer headquarters capable of providing equipment,

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maintenance, administrative, and logistical support. Water wells are engineer construction projectsand must be planned, researched, managed, inspected, and reported just as other projects are. Theunit that the well-drilling team is attached to should provide the team with construction (field ortactical) standing operating procedures (SOP). The team should report well-drilling progress andprocedures according to the SOP.

The well-drilling project should be managed by the critical-path method (CPM). The well-drilling-team’s commander must coordinate and work closely with the construction or operationofficers of the higher headquarters’ unit to ensure timely researching and reporting. When well-drilling teams complete the well-drilling mission, they turn the well over to the operations officer(S3) for disposition. The team then moves to the next project. The S3 arranges transfer of thecompleted well, operating equipment, and technical specifications to a water-purification team, aninstallation, or a host-nation official.

Well-drilling teams will be in great demand in most TOs. Teams may not be able to return toa well site to perform repairs and keep up with the anticipated work load. The senior engineer willhave to set priorities for the team’s work schedule. He should include repairing existing and recentlydrilled wells in the work estimate. The senior engineer must also determine if the teams have theskills or equipment needed to repair the wells before falling a request.

The engineer unit’s construction section, in coordination with the well-drilling team, shouldprepare a construction estimate to determine the needed support for the well-drilling operation.Team experience and land formations will dictate the length of a well-drilling operation. Staffpersonnel should consider the following when planning for the augmentation of a well-drilling team:

Transportation of the well-drilling team’s equipment and personnel by land, air, or sea,according to the unit movement books and operator manuals.Reconnaissance and route selection to mission sites.WDRT assistance and graphic products from the water-resources data base to select apotential drilling site.Security during movement and drilling operations.Earth-moving assets to clear and level the drilling site and excavate mud pits.Material handling equipment to offload well-completion-kit materials, as needed.Administrative support, including postal and legal services.Logistical support, including all classes of supply and arrangements for mess; petroleum,oils, and lubricants (POL); maintenance; and medical support.Delivery of the initial drilling water supply, if required.Turnover of the completed well to a water-purification team, installation, or host-nationofficial.Well-completion kit or component resupply.Communications support.Reporting procedures.Planning for the next mission.

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3-3. Deploying Teams. Army well-drilling units are considered and organized as a specialized skillengineer team. They are not self-sufficient. These teams depend on an engineer battalion or a higherheadquarters that is capable of providing support needed to accomplish the mission.

A well-drilling team leader must ensure that the unit the team is attached to understands themission and capabilities of a team. Because a well-drilling team is small there is little redundancyand no surplus labor. The leader must request additional personnel needed to complete the mission.A well-drilling team has only the equipment necessary to drill under optimum conditions. A well-drilling team leader must request the following from the engineer unit:

Transportation support of the equipment and personnel by land, air, or sea, according tothe unit movement books and operator manuals.Routes to the proposed drill site.WDRT assistance and graphic products from the water-resources data base and anindication of where the TO commander wants the well.Security during movement and drilling.Clearing and leveling of the drill site.Excavation and maintenance of mud pits.Off loading and transportation of well-completion materials.Administrative support, including postal and legal.Logistical support, including all classes of supply with special emphasis on repair parts.Mess and potable water.Fuel and POL products and continual resupply.Specialized maintenance, evacuation, and on-site welding support.Medical support, including medical-evacuation (MEDEVAC) procedures.Initial water supply and resupply.Timely delivery of pea gravel for gravel packing material.Arrangements to turn over the completed well to the supported unit operations cell.Communications support.Reporting procedures.Resupply of completion-kit materials for next mission.Plans for the next mission.

3-4. Site Preparation. Most sites require some preparation before setting up the drill rig. In ruggedterrain, teams may have to excavate into a hillside. They may have to prepare a drilling platform.Teams should always place the drill rig on stable, level ground. Where excavation is not expedient,teams may have to construct mat or timber platforms to level the rig.

C A U T I O N

Avoid setting the rig up on a fill area.

The rig could overturn on soft soil or fill.

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NOTE: Historically, groundwater coming from its natural environment has been considered ofgood sanitary quality. Because of this, personnel in well drilling must understand the effects welldrilling may have on the surrounding environment. Layers of rock and different formations protectthe groundwater supply from contamination. Drilling a hole through these protective layersprovides an access for bacteria and chemicals that could degrade water quality. Well drillers musttake precautions to ensure that they will not contaminate the well and the aquifer.

Teams must level the site and clear it of obstacles and any potentially combustible materials.If overhead power lines area problem, teams must move the rigs or make previsions for removalof the power lines. The drilling platform (or drilling area) should be large enough so teams cansafely operate each component during the drilling operation.

CLEARANCES: If the power lines have a voltage of less than 50 kilovolts (kv), place the rig atleast 10 feet from the power lines. If the power lines have a voltage of more than 50 kv, place therig 10 feet plus 0.4 foot for every kv over 50 kv from the power lines.

NOTE: Consider all overhead power lines as being energized.

Teams should consider locations for the rig and mud-pit, working areas, and well-completioncomponents and accessories; location for and access to drill pipe racks; and location andmaneuverability of the tender truck. Teams should determine if they need a mud pit before startingthe site preparation. If the drill rig does not have a portable mud pit or if the portable pit does nothave sufficient volume, teams should construct a pit during the site-preparation phase.

3-5.foot

Equipment. Current Army well-drilling and well-completion equipment consists of the 600-well-drilling system (WDS) that includes--

A truck-mounted drilling machine.A truck-mounted tender vehicle.A well-completion kit.

The Army also uses the CF-15-S trailer-mounted 1,500-foot well-drilling machine and 1,500-foot completion kit. The 600-foot WDS replaced the CF-15-S trailer-mounted machine and 1,500-foot completion kit. However, the CF- 15-S may still be found forward deployed for contingencypurposes.

a. 600-Foot WDS. This system is used to support well-drilling requirements. The WDS canbe deployed with minimal preparation and support equipment anywhere in the world. The WDSconsists of--

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An LP-12 rotary well-drilling machine mounted on a NAVISTAR 6-by-6 truck chassis.A support vehicle.A lightweight well-completion kit (including accessories, supplies, and tools needed fordrilling a well).

With the completion kit, drillers can complete a well to a depth of 600 feet using mud, air, ora down-hole hammer with or without foam injection. By adding an auxiliary air compressor and adrill pipe, the 600-foot WDS can drill to depths of 1,500 feet and accommodate the 1,500-foot well-completion kit. The well-drilling machine does not have to be modified when drilling with mud to1,500 feet; however, additional equipment and more drill pipe are required to use the 1,500-footwell-completion kit. Additional equipment includes casing elevators and slips, larger drill bits, and900 feet of additional drill steel. Well-drilling teams should ensure that they have the rig accessorykit for the LP- 12 to be fully mission-capable. The 600-foot WDS is--

Air-transportable.Equipped for air-percussion drilling and for rotary drilling with mud or air.Equipped to drill wells up to 600 feet.Adaptable for drilling to depth of 1,500 feet.Truck-mounted for mobility.A three-mode, water-transfer pumping system.

(1) Well-Drilling Machine. Table 3-1 lists specifications for the LP-12 machine. This machineis a truck-mounted, rotary well-drilling machine that has a 32-foot mast, 3-drum draw worksassembly, rotary table, mud pump, and air compressor (Figure 3-1, page 3-6). The components arepowered by the truck engine through a power take-off (PTO) (subdrive). A hydraulic systemoperates the leveling jacks, mast-raising cylinders, and breakout cylinders. The vehicle is equippedwith attachments to tie down and lift the vehicle during transport. For operation and maintenanceprocedures, see TM 5-3820-256-10.

(2) Support Vehicle. Table 3-2 (page 3-6) lists specifications for the support vehicle. Thisvehicle is truck-mounted with a 1,000-gallon water tank, a hydraulically driven water pump, anelectric fuel pump and fuel-dispensing nozzle, a welder-generator assembly, and an electro-hydraulic crane (Figure 3-2, page 3-7). The support vehicle has a storage area for transporting drillsteel, pipes, collars, hand tools, and operating and accessory equipment for the drilling machine andthe well-completion kit. The support vehicle provides hoisting, winching, pumping, welding,generating, burning, and storing requirements to support field drilling operations. Because of theseprovisions, additional equipment needs are reduced in a well-drilling operation. For operations andmaintenance procedures, see TM 5-3820-256-10.

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(3) Well-Completion Kit. This kit consists of equipment needed to complete a 600-foot well.It consists of polyvinyl chloride (PVC) well casing and screens, a submersible pump with starter,electrical wire, drilling mud, and cement for grouting the completed well (Figure 3-3, page 3-8).The completion kit is an expendable item. Teams use a collapsible drop hose to connect the pumpwith the surface. The hose is extremely lightweight and will not corrode in water (Figure 3-4, page3-9). For instructions on using the kit, see TM 5-3820-256-10. The kit has a portable, steel mudpit, with internal baffling, that eliminates the need for a backhoe or similar piece of earth-movingequipment. This mud pit is designed to recover the drilling fluid that recirculates through the system.This mud pit is of limited size and requires frequent cleaning during a well-drilling operation (Figure3-5, page 3-9).

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b. CF-15-S DrillingSystem.

(1) Well-Drilling Machine.Table 3-3 lists specifications onthis machine. The CF- 15-S is acompact, mobile drilling unitthat can handle exploration andwell drilling using air-rotary,mud-rotary, and down-hole-hammer techniques (Figure 3-6,page 3-10). The machine candrill to a depth of 1,500 feet andis equipped to use the 1,500-footwell-completion kit. The 600-foot well-completion kit mayalso be used with the CF-15-S tocomplete a shallow well. Thedrilling machine is powered byan 8-cylinder, 2-cycle dieselengine coupled to a PTO. Othermajor components include an aircompressor, air-compressordrive, transfer case, auxiliarytransmission, mud pump, mud-pump drive, subdrive assembly,rotary table, rotary-tabletransmission, and a 3-drum drawworks.

An installed hydraulicsystem operates the levelingjacks, mast-raising cylinder,rotary-table cylinder, pulldownand holdback assemblies, andbreakout trailer for mobility.Two lifting slings are welded tothe frame. The sling lifting eyesare located adjacent to the fourleveling jacks. The slings are

used to hoist the entire drilling machine on board a surface carrier. The machine is equipped witha detachable mast for loading the machine on an air carrier. In addition, it is--

Air transportable (C-130).Equipped for rotary drilling with mud, air, or foam circulation.Towable by semitrailer tractor or 5-ton truck (using a dolly).

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(2) Well-Completion Kit. This kit is designed to support the CF-15-S well-drilling machinebut may also be used with the 600-foot WDS (Figure 3-7, page 3-11 ). The kit is an assembly ofmachinery, hardware, and bulk material that is either used up in the drilling process or dedicated tothe water well after the drilling is completed. These kits include the following items:

A 6-, 8-, and 10-inch steel well casing to case the hole.A stainless-steel well screen.Drilling fluid.

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Submersible pump with pump cable and drop pipe. The pipe is capable of pumping 50GPM at 1,245 feet.A 30-kilowatt (kw) generator.All necessary plumping to configure the well from the well screen to the pump dischargeinto a 3,000-gallon, portable, collapsible water-storage tank.

The kit has enough material to drill and complete a production water well in consolidated orunconsolidated formations anywhere in the world. These kits are maintained as depot war stocksuntil needed. Each kit weighs over 60,000 pounds. For a description of all components, see SupplyCatalog (SC) 3820-97-CL-EO1.

3-6. Transportation.

a. 600-Foot WDS. This system can be transported by three C-130s, two C-141s, one C-5, orby rail. A minimum amount of equipment disassembly is required.

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(1) C-130. The well-drilling team and the organic and support equipment require up to sixC-130s for transportation. Support equipment includes a 5/4- and 5-ton truck with a 10-ton trailer.The well-drilling machine and support vehicles have roll-on, roll-off capabilities (Figure 3-8, page3-12). The load configuration for transportation by C-130 is as follows:

The well-drilling rig and two pallets of components and accessories are on the firstaircraft.The support vehicle and one pallet of components are on the second aircraft.The pipe dolly with two pallets of completion material is on the third aircraft (Figure 3-9,page 3-12).

(2) C-141. The WDS is transportable in a C-141 without any special disassembly, but parkingshoring is required for the front axle of the drilling rig.

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(3) C-5. The WDS istransportable in itsoperational configurationwithout any disassembly orspecial procedures.

(4) Rail. No specialdisassembly is needed totransport the WDS by rail.Also, the 6-by-6 truck chassistransports provide excellentroad and cross-countrymobility.

b. CF-15-S DrillingSystem. This system can bedeployed by air, sea, orground. The machine is notrapidly deployable by aircraftand requires extensivematerial-handling supportequipment. Though designedfor transport in a C-130,almost 12,000 pounds mustbe removed to meet a 13,000-pound weight restriction peraxle in the aircraft. Figure3-10 shows the componentsthat must be removed fromthe rig for a C-130 transport.Loss of any of these items intransit will render themachine inoperable.

It takes about 6 to 8 hoursto prepare the rig for loadingand 10 to 12 hours to

reassemble the rig. Because the rig must be partially disassembled, material handling equipment,such as a crone or forklift, must be available at the aerial port of embarkation (APOE) and aerialport of debarkation (APOD). The prime mover must be transported on a separate aircraft, whichmeans that the mover may not be available at the forward airfield to remove the rig.

(1) Air. Six C-130s are needed to transport the CF-15-S drilling machine and completion kit.The CF-15-S rig is not transportable in a C-141. Even in the reduced weight configuration, the rigstill exceeds the maximum allowable weight per axle. The machine may be transported by C-5s inits operational configuration without any special procedures or disassembly. See Technical Order(TO) lC-130A-9 for specific loading instructions.

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(2) Ground. For ground transportation, the kit requires 7 long-bed, 5-ton cargo trucks or 3tractor-trailer trucks.

(3) Rail. For rail loading, the mast must be removed and secured to one flat car. The rest ofthe drilling machine is mounted on a second flat car.

3-7. Drill-Rig Setup. Before setup, teams must inspect the rig for damages during deployment.During the inspection, they should perform preventive maintenance checks. After inspecting therig, setup can begin. Teams should use the following steps for the setup:

Step 1. Position the drill rig. The rotary table should be over the center of the holelocation. If you are using a portable mud pit, set the pit in position with the overflowpipe over the well location. Extend the rotary table (on the drill rig) to the workingposition, and move the rig, if required, to the final position. Set the rotary table exactlyover the well or the mud pit overflow pipe.Step 2. Position and extend the leveling jacks. The jacks level the drill rig, remove theweight from the rig’s suspension system, and provide a stable, rigid drilling platform. Insoft soil, you may have to use timber under the jack pads to prevent the rig from sinkinginto the soil.Step 3. After extending the jacks, raise the drilling-rig mast (Figure 3-11, page 3-14).Check for overhead obstructions or power lines. Periodically, release the hoisting drumand auxiliary drum brakes to allow slack in the cables. After fully raising the mast, lockit into position and recheck the drill rig’s level.Step 4. Check and, if necessary, connect the discharge piping. Depending on the typeof drilling operation, connect either the air compressor or the mud pump to the standpipeon the mast.Step 5. Install or dig a mud pit, whichever is applicable. Make the appropriateconnections to the mud pump to ensure continuous cumulation of the drilling fluid.

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When drilling past 600 feet, thekelly draw works must be rigged with adouble block to create a three- or four-

part line (Figure 3- 12). Using the sheave block provides a mechanical advantage that allows heavierweights to be lifted. By using sheaves, the load is supported by two or more lines. This providestwo or three times the tensile strength used to hold the load. Also, using more lines allows the winchto pull on the first layer of the cable on the drum, which increases the capacity and saves wear onthe chains. Table 3-4 is an example of Figure 3-12. For more information on drill-rig setup, seethe operator’s manual for the drilling system you use.

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3-8. Drilling Fluid. If you use rotary drilling with mud, connect or place the suction line of themud pump in the mud pit and fill the pit with water. Close the standpipe valve and prime the mudpump. Mix the drilling fluid in the mud pit by slowly circulating fluid through the mud pump andadding drilling mud to the mixing hopper (Figure 3- 13). The drilling fluids usually used for mixingmud are a Wyoming-type bentonite drilling additive (Quick-Jel) or an organic or inorganic polymerfluid (Revert or E-Z Mud). Mix the additives until you reach the desired weight and viscosity forthe drilling mud. Chapter 5 details mud mixing.

3-9. Well-Drilling Operations. Before you start drilling, youmust select a drill bit. Consider the well diameter and the type offormations you will drill through. The types of bits are--

Drag bits. Use these bits for soil, unconsolidatedmaterials usually found near the surface.Tricone roller-rock bits. Use these bits for a variety ofmaterials from soft formations through hard rock(Figure 3-14). The bits are available in differentdegrees of hardness. Bits used for softer formationshave longer teeth on the roller cones.

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a. Starting the Operation. The first operation is spudding in (starting the borehole). Beforeyou start drilling the actual hole, consider drilling a 6- to 71/2-inch test hole. Doing so will ensurethat you dig the larger hole straight, and you should locate the aquifer quicker. Use the followingsteps to start the drilling operation:

Step 1. Make up the drill bit on the kelly and lower the bit to the ground.Step 2. When the bit contacts the ground, engage the rotary table and clutch to startdrilling.Step 3. After the borehole advances 6 to 12 inches, engage the mud pump to startcirculating the drilling fluid (which will be mud or air).Step 4. After drilling down the kelly, stop the rotation and raise the kelly about 4 inchesoff the bottom of the borehole. Circulate the drilling fluid until all drill cuttings areremoved.Step 5. Disengage the mud pump, raise the kelly, and remove the bit.

b. Finishing the Operation. After spudding in, use the following steps to finish the operation:

Step 1. Makeup the bit on a drill collar. Suspend the collar and bit in the borehole usingthe hoist or sand line. Support the drill collar in the hole using slips.Step 2. Clean and lubricate the threads on the kelly bar and makeup the kelly to thethreads (Figure 3-15).Step 3. Remove the slips, and lower the kelly so that the drive bushing engages the rotarytable and that the tool string is lowered to the bottom of the borehole.Step 4. Engage the mud pump again and continue drilling. After drilling down the kelly,circulate the drilling fluid until the cuttings are removed. Raise the tool string until thetool joint is 4 to 6 inches above the rotary table.Step 5. Disengage the mud pump and set the slips to support the tool string. Disconnectthe kelly from the string and set the kelly back to the cradle position.Step 6. Run out the sand line, remove the end cap, and connect a hoisting plug to anotherdrill collar or to a joint of drill pipe.Step 7. Lift the drill steel with the hoist line or sand line and place the hoisting plug onthe drill steel (Figure 3-16, page 3-20).Step 8. Remove the lower end cap. Clean and lubricate the threads. Make up the threadsto the string in the hole with pipe wrenches.Step 9. Lift the entire string slightly and remove the slips. Lower the string until the tooljoint is 4 to 6 inches above the rotary table and the slips are reset.Step 10. Make up the kelly to the tool string, remove the slips, engage the mud pump,lower the string to the bottom of the borehole, and continue drilling. Repeat the processuntil you reach the desired depth.Step 11. Reverse the process to come out of the borehole.

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W A R N I N G

To prevent injuries from shifting loads,use taglines when hoisting a load.Attach long taglines to the load to

maintain control.

Finally, if the drill rig breaksdown or needs repair ormaintenance, record theinformation in the log. Theinformation in the driller’slog can provide you with aninsight into local conditionsand help you determinewell-screen locations andplan for additional or futurewell installations. Alwaysplace the screen sections intothe aquifer and not at thebottom of the hole.

3-10.Sampling and Logging. You should takesamples and record them on every well drilled.During the drill operation, take samples of thecuttings in the drilling fluid (Figure 3-17, page3-18). Record the samples in a driller’s logaccording to basic classifications (sand, clay, orgranite) and describe their color and consistency(coarse or free) when possible. Also, record theapproximate depth of the sample. If you wantsamples from a specific depth, stop the drillingoperation and let the drilling fluid circulate untilthe cuttings reach the surface.

Other information you should record areadvance rate, reaction of the drill rig, any loss ofcirculation, and changes in drilling fluidconsistency. Periodically, check the drilling fluidfor viscosity, weight, and sand content. Log thetest results and any adjustments you made.

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3-11. Casing and Well Screen.Depending on the construction method, setthe well casing in the well before or at thesame time as you set the well screen. (The600-foot WDS has no surface casing.) Ifthe borehole has a tendency to cave induring drilling, install the casing whiledrilling but before reaching the desireddepth. (Use this procedure when drilling inloose, unconsolidated materials.) Wheninstalling the casing before the well screen,such as surface casing, the casing must belarger than the screen. Therefore, use alarger drill bit than the one used to completethe screen portion of the borehole. Thedecision to use surface casing should bemade before mobilizing and should bebased on the geologic information about thesite.

a. Surface Casing. Use the followingsteps to install the surface casing:

Step 1. Drill the borehole to a predetermined depth, and remove all the cuttings bycirculating the drilling fluid. Withdraw the drill string and remove the bit.Step 2. Set the kelly back in the cradle. Connect the elevators to the first section ofsurface casing that is lifted over the borehole by using a casing elevator and the hoist orby using a sand line (Figure 3-18).Step 3. Lower the casing into the well and set the slips (Figure 3- 19), which suspend thecasing in the well, in the spider bowl (Figure 3-20).Step 4. Disconnect the elevator. Hoist the next casing section with the elevator, andplace it in the first section. Join the two sections. Slightly lift the string of casing, andremove the elevator from the lower section. Lower the casing, and repeat the processuntil you suspend the last casing section in the well.Step 5. Grout the casing in place with a cement grout. After the grout sets (about 24hours), resume drilling operations using a drill bit that will fit inside the surface casing.Drill the well to the desired depth, and case and screen the lower section of the well, usingthe single-string method.

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b. Screening. You can use the following method to install screens:

Step 1. Place a casing section in the well. Cap the casing on the lower end so materialsfrom the bottom of the well will not enter the well.Step 2. Suspend a screen section over the well and attach the screen section to the casingsection.Step 3. Lower the screen and casing section. Suspend them in the well either by theelevator resting on the rotary table or by slips in the spider bowl.Step 4. Add casing until the screen reaches the desired depth.

Chapter 5 discusses other methods of screening.

c. Filtering and Backfilling. The last procedure when installing screen and casing is to placea gravel-pack filter around the screen and backfill material around the casing. If you place the screenin material such as gravel or very coarse sand, you may not need a gravel pack. Place the gravelfilter material around the outside of the casing. Deposit the material to the bottom of the well. Addgravel to about 5 feet from the top of the screen. (Use the sounding method to determine the levelof the gravel.) Add impervious backfill around the casing from the gravel pack to about 10 to 20feet from the surface. If you use grout instead of impervious material, add a couple of feet of clayabove the gravel to prevent the grout from entering the gravel filter. Bring the grout to the surface.

3-12. Well Development Frequently, when a well is frost installed, the efficiency (production perfoot of drawdown) is not satisfactory, and you must develop the well either by pumping or surgingor both. Developing a well removes the remaining drilling fluid, breaks down any filter cake buildupon the borehole wall, and flushes the fines in the formation (adjacent to the grovel pack) into thewell. Make sure that you pump the well of all fine sediments and sand with an airlift before installingthe submersible pump. If you do not, the pump and components will wear out prematurely. Todevelop a well, pump or blow the drilling fluid out of the well. Agitate the water in the well toproduce an alternating in and out flow through the well screen (or gravel pack). There are severalmethods available to develop a well. The simplest method follows:

Step 1. Attach a weighted plunger or surge block to the sand line. Lower the surge blockinto the well below the water level but above the screen.Step 2. Lift the block and then drop the block 3 to 4 feet, repeatedly, to surge the well.Continue this action for several minutes.Step 3. Remove the surge block and lower a bailer into the well. All of the sand thatwas pulled into the well is bailed from the sand trap.Step 4. Repeat the process, noting the amount of sand brought into the well each time.Development is complete when 5 milligrams or less of sand per liter of sampled water isremoved.Step 5. Sanitize the well with calcium hypochlorite.

3-13. Sanitary Seals. All wells must have a sanitary seal to prevent contamination from surfacerunoff. Mix cement grout and place it in the annulus between the well casing and the borehole wall.Extend the grout from the surface to the top of the backfill material (30-foot minimum). You shouldalso pour a concrete platform (about 4 feet by 4 feet) around the casing at the surface with the casingextended at least 1 foot above the surface. The upper surface of the slab and the surrounding area

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should be gently sloping away from the well for better drainage. In addition to a surface grouting,you need to install a well seal (a type of bushing or packing gland) to prevent foreign materials fromentering the inside of the well casing. You normally install the well seal when you install the pump,which is after you complete all development, testing, and disinfecting.

3-14. Pumping Tests. After installing a well, you should perform a pumping test. The test willshow you if the well can produce the required amount of water. If the well is considered permanent,the pumping test should help you evaluate any future performance deterioration. Evaluationparameters are flow rate, time, and drawdown in the well.

Before you start the test, place a sounding device, such as an M-Scope, in the well to measurethe water level during the test. You must also measure and regulate the flow rate during the test.The most proficient way to measure the flow rate is with a flow meter. However, you can use acalibrated container and a stop watch. Use the following procedures to perform the pumping test:

Step 1. Temporarily install a pump in the well below the anticipated drawdown depthbut above the screen.Step 2. Measure the static water level and start the pump. During the test, one teammember should monitor the flow rate and try to keep the flow rate constant.Step 3. Record the drawdown with the flow rate. Take early readings quickly; thenspread out the readings as testing progresses. An ideal reading schedule would be theinitial reading and then a reading at 30 seconds, 1 minute, 2 minutes, 4 minutes, 8 minutes,15 minutes, 30 minutes, 1 hour, 2 hours, and so forth. You must record the exact timesyou take readings of the drawdown and flow-rate measurements. The length of a testusually depends on the purpose of the well, the urgency for water, and the time available.On small water supplies, you can perform an adequate evaluation in 4 to 5 hours. Forlarge, permanent supplies, tests could take from days to weeks. The GPM, footage ofdrawdown, and available drawdown give an immediate indication of the well’s capacity.If the pump from the well-completion kit is capable of producing more water than thewell can, you should put a throttle or a valve on the pump. Doing so will help regulatewater extraction and will prevent pump damage.Step 4. Set and adjust the pump. The well is now ready for use or for connecting to atreatment, storage, and distributions system.

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Chapter 4Pumps

4-1. Fundamentals.

a. Pump Types. Pumps maybe classified according to use (for shallow or deep wells), design(variable or positive displacement), or method of operation (rotary, reciprocating, centrifugal, jet,or airlift). This chapter deals with shallow- and deep-well pumps. Shallow-well pumps (suction-liftpumps) are normally installed above ground, on or near the top of the well casing. Deep-well pumpsare installed in the well casing with the pump inlets submerged below the pumping level. Theseinlets are always under a positive head and do not require suction to move or pump the water.

b. Selection Criteria. Consider the following items when selecting a pump:

Size of the well.Quantity of water to be pumped.Drawdown and pumping levels.Type of available power.Yield of the well.Estimated total pumping head.

Well yield is frequently overlooked when selecting a pump for small wells. Installing a pumpthat can handle a large discharge capacity can either temporarily drain a small well or exceed themaximum possible suction lift. Therefore, pumping requirements and well characteristics must bematched to determine the optimum pump for each installation. Table 4-1 (page 4-2) provides ageneral guide for use in pump selection. Military well drillers deploying with well-completion kitswill normally use the deep-well submersible pumps that are supplied with the kits.

4-2. Shallow-Well Pumps. These pumps are limited to the depth from which they can lift water.At sea level, the practical limit is 22 to 25 feet for most pumps. This value decreases about 1 footfor each 1,000-foot increase in elevation above sea level. The operative principle of a shallow-wellpump is similar to drinking through a strew. A partial vacuum is created, and the difference betweenthe pressure inside the straw and the liquid outside the straw forces the liquid upward to a newequilibrium.

A pump exhausts air from the intake line, thus lowering the pressure on the intake side belowatmospheric pressure. The atmospheric pressure on the water in the well then forces the water upthrough the suction line into the pump. The atmospheric pressure is the only force available to liftwater to the pump. At sea level, the force is about 14.7 pounds per square inch (psi) (about 34 feetof water). The maximum is never reached because pumps are not 100 percent efficient and becauseother factors (water temperature and friction or resistance to flow in the suction pipe) reduce thesuction lift. Since a partial vacuum is required in the suction line, the line must be airtight if thepumps are to function properly. Threaded joints must be carefully sealed with pipe-joint compoundand all connections to the pump must be tight.

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a. Pitcher Pump. This is a surface-mounted, reciprocating or single-acting piston pump (Figure4-1). The pump has a hand-operated plunger that works in a cylinder designed to be set on top ofthe well casing. The suction pipe screws into the bottom of the cylinder. The plunger has a simpleball valve that opens on the downstroke and closes on the upstroke. Usually, a check valve at thelower end of the cylinder opens on the upstroke of the pump and closes on the downstroke.continuous upstroke and downstroke actions result in a pulsating flow of water out of the dischargepipe. By lifting the pump handle as high as possible, the check valve (lower end of the cylinder)will tilt when the plunger is forced down on top of the valve. Tilting the check valve allows thepump and suction line to drain.

To reprime the pump after draining, pour water inthe cylinder from the top of the pump. To maintainthe pitcher pump, renew the plunger, check the valveleathers, and clean the suction pipe. Clean the suctionpipe when it becomes clogged with sand, gravel, orother material. The pump will be noisy and the pumphandle may fly up when released during thedownstroke.

b. Rotary Pump. These pumps use a system ofrotating gears (Figure 4-2) to create a suction at theinlet and force a water stream out of the discharge.The gears’ teeth move away from each other at theinlet port. This action causes a partial vacuum and thewater in the suction pipe rises. In the pump, the wateris carried between the gear teeth and around both sidesof the pump case. At the outlet, the teeth movingtogether and meshing causes a positive pressure thatforces the water into the discharge line.

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In a rotary gear pump, water flows continuously and steadily with very small pulsations. Thepump size and shaft rotation speed determine how much water is pumped per hour. Gear pumpsare generally intended for low-speed operation. The flowing water lubricates all internal parts.Therefore, the pumps should be used for pumping water that is free of sand or grit. If sand or gritdoes flow through the gears, the close-fitting gear teeth will wear, thus reducing pump efficiencyor lifting capacity.

c. Centrifugal Pump. These are variable displacement pumps in which water flows by thecentrifugal force transmitted to the pump in designed channels of a rotating impeller (Figure 4-3).A closed case, with a discharge opening, surrounds the impeller. The case has a spiral-shapedchannel for the water. The channel gradually widens towards the outlet opening. As water flowsthrough the channel, speed decreases and pressure increases. The hydraulic characteristics of thepump depend on the dimensions and shape of the water passages of the impeller and the case.

The centrifugal pump works as follows:

Water enters the pump at the center of the impeller and is forced out by centrifugal force.(You may have to fill the pump and suction pipe with water before starting the pump.)The expelled water forces the water in the casing out through the discharge pipe,producing a partial vacuum in the center.Atmospheric pressure acts on the surface of the water in the well and forces more waterup the suction pipe and into the impeller to replace the expelled water.

(1) Head. Head is thepressure against which a pumpmust work the suction-lift andfriction losses and the systempressure that the pump mustdevelop. If the head is increasedand the speed is unchanged, theflow rate will decrease. Toincrease the flow rate, you mustincrease the speed or decrease thehead. If you increase the headbeyond the pump’s (shutoff head)capacity, water will not bepumped. The impeller only churnsthe water inside the case; theenergy expended heats the waterand the pump. If such actioncontinues, enough heat maydevelop to boil the water andgenerate steam causing theimpeller to rotate in vapor ratherthan water. With no coolant, thebearings seize, resulting in severepump and possible motor damage.

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(2) Connections. You may have to use several pumps to meet head or flow requirements. Youcan connect the pumps either in series or in parallel. If you connect two centrifugal pumps in series(the discharge of the first connected to the suction of the second), the discharge capacity stays thesame. However, the head capacity is the sum of both pumps head capacities. The increased headcapacity is only available as discharge head. You will not gain any appreciable increase in suctionlift. You can obtain the same effect by using a multistage pump that contains two or more impellerswithin one casing.

If you connect two centrifugal pumps in parallel (both suctions are connected to the intake lineand both discharges connected to the discharge line), the discharge head is the same as that of theindividual pumps. The discharge capacity is close to the sum of the capacities of both pumps. Theincreased flow rates result in extra friction losses that prevent the combined flows from being theexact sum of the two pumps.

d. Self-Priming Pump. This pump has a priming chamber that makes repriming unnecessarywhen the pump is stopped for any reason other than an intentional draining. The pump is mountedon a frame with and driven by a two-cylinder, three-horsepower military standard engine (Figure4-4, page 4-6). The unit is close-coupled. The impeller is secured to an adapter shaft that is fastenedand keyed to the engine stub shaft. A self-adjusting mechanical seal prevents water from leakingbetween the pump and the engine. The pump is designed for optimum performance with a suctionlift of 10 feet. You can operate the pump at greater suction lifts, but the capacity and efficiency ofthe unit are reduced proportionately.

(1) Installation. Install the pump as close to the source of water supply as possible to minimizethe required suction lift. Install full-sized suction piping and keep friction losses as low as possibleby using the least possible number of pipe fittings (elbows, bents, unions). To ensure that joints donot leak use pipe cement or teflon tape on all joints. If you use a suction hose, try to ensure thatthe hose is as airtight as possible. If you have to remove the suction or discharge piping or hosefrequently, you should make the connections with unions to reduce wear on the pump housing.

(2) Priming. To prime the pump, remove the priming plug on top of the pumping case, andpour water into the pump case to the discharge-opening level. Failure to fill the priming chambermay prevent priming. If the pump takes longer than 5 minutes to prime, a mechanical problemexists. A self-priming pump is normally primed from a 10-foot suction lift in 2 minutes or less,depending on the length and size of the suction pipe. If you use a valve in the discharge line, youmust open it wide during priming.

If the pump fails to prime, look for the following:

Plugged priming hole.Air leak in suction pipe or hose.Collapse of lining suction hose.Plugged end of suction pipe or suction strainer.Lack of water in pump housing.Clogged, worn-out, or broken impeller.Worn or damaged seal.

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4-3. Deep-Well Pumps.

a. Submersible Pump. This is a centrifugal pump closely coupled with an electric motor thatcan operate underwater. The pump is typically multistage containing two or more impellers(depending on head requirements) housed in a bowl assembly. Because the system is designed forunderwater operations, it has a waterproof electric motor, watertight seals, electric cables andconnections. The motor is located beneath the bowl assembly with the water intake screen betweenthe two units.

Military well-completion kits contain the submersible pump (Figure 4-5). The pump produces50 GPM at 600 feet and is powered by a 15-horsepower, 460-volt, 3-phase electric motor. Thepump comes with 700 feet of electrical conductor cable and 660 feet of 2-inch drop hose that supportsthe pump and brings the water to the surface distribution system. Currently, the submersible pumpis the standard in deep-well, high-production systems.

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The following improvements have made thesubmersible pump a reliable pump:

Motors, cables, and seals have very lowmaintenance requirements.Noise levels are reduced because the motoris located in the well.Motor operates at a cooler temperaturebecause it is submerged.System does not require long drive shafts andbearings, so maintenance problems anddeviations in vertical well alignment are notcritical factor when using this pump.

The main disadvantage with the pump is that theentire pump and motor assemblies must be removedfrom the well if repairs or services are required.

b. Turbine Pump. The turbine (line shaft) pump isa shaft-driven, centrifugal pump. The pump is hung in

a well at the lower end of a string of pipe called the column pipe. The shaft, which drives the pump,runs through the column pipe and extends from the pump to the ground surface where it is connectedto a pump-head assembly. Bearings in the column pipe are used to stabilize the shaft. The turbinepump (Figure 4-6, page 4-8) is a multistage pump containing several impellers or bowl assemblies.The main advantage to the turbine pump is the accessibility to the power source. The power sourceis either a hollow-shaft electric motor or a reciprocating engine connected by a right-angle driveand is located above ground. The main disadvantages are maintenance requirements for the shaftand bearings and the requirement that the well be vertical with no deviations for installation.

c. Helical-Rotor Pump. This pump is a positive-displacement-, rotary-screw-, or progressing-cavity-type pump (Figure 4-7, page 4-9). The pump is designed for relatively low-capacity, high-lift wells that are 4 inches or larger in diameter. The main elements of the pump are a highly polished,stainless-steel helical rotor, a single-thread worm; and an outer rubber stator. The rotor is locatedin the stator. During the rotation process, the rotor forces a continuous stream of water forwardalong the cavities in the stator producing a uniform flow. The helical-rotor pump is designed toproduce 50 GPM at 1,800 revolutions per minute (RPM) against a 250-foot head.

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d. Jet Pump. This pump is acombination of a surface centrifugalpump, down-hole nozzle, and venturiarrangement (Figure 4-8). It can beused in small diameter wells thatrequire a lift of 100 feet or less. Thepump supplies water, under pressure,to the nozzle. The increase in velocityat the nozzle results in a decrease inpressure at that point, which in turndraws water through the foot valveinto the intake pipe. The combinedflow then enters the venturi where thevelocity is gradually decreased and thepressure head recovered. The excessflow is discharged at the surfacethrough a control valve, which alsomaintains the required recirculatingflow to the nozzle.

diameter.Easy accessibility to all moving parts at theground surface.

A jet pump’s efficiency is low compared to an ordinarycentrifugal pump. However, other features make the jetpump a desirable pump. They are--

Adaptability to wells as small as 2 inches in

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Simple design resulting in datively low purchase and maintenance costs.

4-4. Air-Lift Pumps.

a. Principle. Water can be readily pumped from a well using an air-lift pump. There are noair-lift pumps in the Army supply system; however, in the field, you can improvise and make apump using compressed air and the proper piping arrangement. The assembly consists of a verticaldischarge (eductor) pipe and a smaller air pipe. Both pipes are submerged in the well below thepumping level for about two-thirds of the pump’s length. The compressed air goes through the airpipe to within a few feet of the bottom of the eductor pipe and is then released inside the eductorpipe. A mixture of air bubbles and water forms inside the eductor pipe. This mixture flows up andout the top of the eductor pipe. The pumping action that causes water to rise as long as compressedair is supplied is the difference in hydrostatic pressure inside and outside the pipe resulting fromthe lowered specific gravity of the mixed column of water and air bubbles. The energy operatingthe air lift is contained in the compressed air and released in the form of bubbles in the water. Figure4-9 shows the operating air-lift principle.

WARNING

Air and fluids under pressure can cause injury.Make sure all air couplings are tight and that

lines and hoses are in good condition.

You should arrange an air liftwith the air pipe inside the eductorpipe (Figure 4- 10). You can use thisarrangement for test pumping wellsand for well development. You canuse the well casing for the eductorpipe. However, to pump sand andmud from the bottom of a well duringwell development and completion,use a separate eductor pipe. This typeof pump is also useful in wells that,because of faulty design, producesand with the water. This conditionwill quickly create excessive wear onmost pumps. By setting the educatorpipe to the bottom of the screen, sandwill be removed before it fills thescreen.

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b. Installation Design.

(1) Submergence. Submergence is the proportion (percentage) of the length of the air pipethat is submerged below the pumping level. Use the following formula and Figure 4-11 (page 4- 12)to determine submergence percentage:

where–

x = vertical distance from A to C.y = vertical distance from C to D.

(2) Air Pressure. To calculate the requiredair pressure to start the air lift, you must knowthe length of air pipe submerged below the staticlevel. See Figure 4-11 (page 4-12), area frompoint B to point D, for the starting air pressure.Divide the area from point C to D by 2.31(constant/conversion factor) to get the requiredair pressure (psi).

(3) Compressors. The 350 cubic feet perminute (cfm) compressor on military drillingrigs, such as the LP-12, is sufficient for operatingan air lift. With a submergence of 60 percent, alift not exceeding 50 feet and the compressordelivering 350 cfm of air, a well can be pumpedat over 200 GPM. If you need more air, useanother compressor in parallel. The maximumpressure that the compressor will produce is 200psi, which is enough to start an airlift with about420 feet of air pipe submerged.

CAUTION

Operate compressors upwind of the drillingrig. If you do not, dust could damage the

equipment.

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(4) Correct Air Amounts. For efficiency, the compressor must deliver the correct amount ofair. Too much air causes excessive friction in the pipe lines and waste of air from incompleteexpansion in the discharge pipe. Too little air results in a reduced yield and a surging, intermittentdischarge. To calculate air-compressor requirements, see Table 4-2.

(5) Performance and Efficiency. The performance and efficiency of an air lift vary greatlywith the percent of submergence and the amount of lift. Generally, a submergence of 60 percentor more is desirable. If a well has a considerable pumping-level depth, you will have to use a lessersubmergence percent. However, if the submergence is too low, the air lift will not operate. SeeTable 4-3 (page 4-14) for performance data for air-lift pumps corresponding to differentsubmergence conditions and lifts. The values are for properly proportioned air and eductor pipeswith minimum frictional losses. The efficiencies indicated in terms of gallons of water per cubicfoot of air probably cannot be fully attained in military field operations.

(6) Foot Piece. For best efficiency, the end of the air pipe should have a foot piece (Figure4-10, page 4-11). This device breaks the air into small streams so that the bubbles formed will beas small as possible. You can make a foot piece by drilling numerous small holes in a short sectionof pipe.

(7) Discharge Pipe. You can approximate the discharge-pipe length from Table 4-3. Lowersubmergence than those shown result in a lower pumping efficiency. The planned pumping ratemust not cause an excessive drop in the water level, reducing the submergence. The two chief lossesin the discharge pipe are air slipping through the water and the water friction in the discharge line.As the velocity of discharge increases, slippage decreases and friction increases. Eductor intakeloss occurs at the lower end of the pipe due to friction and to the energy required to accelerate theflow of water into the pipe.

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Part Two. Well Drilling

Chapter 5Well-Drilling Methods

5-1. Mud Rotary Drilling. Rotary drilling with mud is the most widely used method for water-wellconstruction. A rotary drill rig has three functions: rotating the drill string, hoisting the drill string,and circulating the drilling fluid. A bit is rotated against the formation while mud is pumped downthe drill pipe, through ports in the bit, and back to the ground surface through the annulus betweenthe drill pipe and the borehole wall. (Table 5-1, page 5-2 shows the relative performance of drillingmethods in various geologic formations.) Drill cuttings rise to the ground surface in the drillingfluid. Rotary drilling is sometimes called mud rotary drilling. Drill pipes or rods are joined to a bitto form the drill string. The drill pipe is the link transmitting torque from the rig to the bit, and thepipe carries the drilling fluid down the hole.

a. Rotary Rigs. Rotary rigs vary in design. Drilling rigs are truck- or trailer-mounted and arepowered by an on-board engine or by a PTO from the truck transmission. Power is delivered to thevarious components through hydraulic pumps and motors or through mechanical transmissions andclutches and geared on roller-chain drives. Many drill rigs may use both mechanical and hydraulicdrives. Torque is applied to the drill string, which rotates by using three basic designs—rotary table,top head, and quill-and-drive bar. Military drilling machines use rotary table drives.

(1) Rotary Table. The rotary table is a rotating platform that transmits torque to the drill rodthrough the kelly. The kelly, which is attached to the mud swivel, is the uppermost section of thedrill string that passes through the rotary table. The drill string may be square, hexagonal, or roundwith grooves or flukes on the outside wall. The drive kelly bar slides through the rotary table whilerotating. By removing the kelly bar, you can add drill pipe and work the pipe through the open holein the rotary table. The rotary table normally is a mechanical, positive drive mechanism.

(2) Top Head. The top-head drive uses a power swivel. Torque is applied at the top of thedrill string. The top-head mechanism moves down along the rig mast as the boring is advanced andis raised to the top of the mast to add a length of drill pipe. Top-head-drive drill rigs do not use akelly bar. Most top-head drives are powered by hydraulic motors capable of variable speeds ratherthan positive constant rotation.

(3) Feed Drive. Rotary rigs are equipped with a mechanism to apply a downward thrust to thedrill string. This mechanism is called a pulldown or feed drive.

Generally, two roller chains apply the thrust for rotary tables. The chains are attached to thekelly swivel and extended over sprockets at the top of the mast and under the rotary table. On olderrigs, the sprockets under the rotary table are powered mechanically through a PTO and clutch. Thepulldown chains on modem drill rigs are powered by a hydraulic motor, which provides better thrustcontrol.

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The thrust mechanism on most top-head rigs is a pair of roller chains consisting of two chainsections. One end of each section is attached to the swivel at the top of the kelly bar. The otherends are dead-headed to the top and bottom of the mast. Sprockets at the top and bottom of themast act as idlers. Chains are powered in either direction by hydraulic rams. These rams applythrust and are used in a hold-back mode to reduce the bit load of the weight due to the drill string.This chain mechanism is also the main hoist for lifting the drill string.

(4) Mud Pump. A mud pump (Figure 5-1) on a rotary drill is usually a positive-displacement,double-acting piston pump with capacities ranging from one to several hundred GPM at pressuresup to several hundred psi. Power may be provided through a mechanical PTO and clutch, with orwithout a separate transmission. Power may also be provided by a separate engine or a hydraulicor air motor. Other types of pumps are often used successfully, but their limited pressure capacitymay jeopardize the success of the drilling operation. Most well-drilling machines have dual piston,double-acting, positive-displacement mud pumps. Pump capacity (volume and pressure) can limitthe effective depth of a drilling operation. The horsepower required to drive a mud pump oftenexceeds the power required to hoist and rotate the drill string.

(5) Hoists. Man drill-head hoists (draw works) are

(1) Tricone Roller Bits. These bitsbit consists of three cone-shaped rollers

mechanically or hydraulically driven wire-line winches.On top-head rigs, the pulldown chains are used as the mainhoist. Many drill rigs have auxiliary hoists for handlingpipe and other equipment and for bailing. The bailingdrum usually has less lifting capacity and a faster spoolingrate than hoisting drums. Bailing drums can spool severalhundred feet of wire line, which is sufficient to reach thebottom of most wells. Auxiliary hoists may be poweredmechanically or hydraulically.

b. Drill Bits. See Table 5-2 (page 5-4) forrecommended rotating speeds for all sizes and types of bitsin various formations. See Figure 5-2 (page 5-4) for bitselection. Appendix E discusses characteristics andmaintenance for drill bits.

are best suited for brittle or friable materials. The triconewith steel teeth milled into the surfaces. Tooth locations

are designed so that as the cone rotates, each tooth strikes the bottom of the hole at a differentlocation. Drilling fluid is jetted on each roller to clean and cool it. The cutting action is a progressivecrushing under the point load of each tooth. Roller bits designed for rock, rocky soil (gravel), andsoft formations (shale) have long teeth. The bits for harder formations have smaller, stronger teeth.The gauge teeth on bits designed for very hard rock are reinforced with webs. For extremely hardformations, milled teeth are replaced with connected carbide buttons.

(2) Drag Bits. These bits are used in soil and other unconsolidated materials. The blades aredesigned so that they cut into the formation with a carving or scraping action. Drag bits may havemultiblade, hardened-steel, finger-shaped teeth or may have connected carbide-reinforced cuttingedges.

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c. Rotary Operation. Standard rotary drilling involves the bit rotating against the formation.Drilling fluid is pumped through the drill string and face of the drill bit and backup the annulus tothe surface. The rotary action of the bit loosens the material, while the drilling fluid cools andlubricates the drill pipe and bit and carries cuttings to the surface. The drilling fluid is under highhydrostatic pressure and supports the wall of the borehole against caving. The properties of thedrilling fluid are important to the drilling operation. Well drillers must have knowledge of drillingfluids and their use for successful rotary drilling. Drillers must also know about drilling-fluidadditives used to prevent problems in drilling. Preventing drilling problems, such as an unstableborehole wall or a stuck tool, is easier than fixing the problem after it occurs. See paragraph 5-1e(page 5-8) for information on drilling fluids.

Before drilling with mud, build a mud pit. The pit may be either a portable pit or an excavatedmud pit. The decision depends on the hole depth and the alternatives available. See paragraph5-1e(9) (page 5-18) for more information on mud pits.

d. Variables. Bit design, weight onbit, rotation speed, fluid consistency, andcumulation pressure and velocity affectrotary drilling. Experience helps thedriller handle unique problems andconditions. Continue to experimentwherever you drill to develop the bestdrilling procedure. Before starting thehole, plumb the kelly to provide a straighthole (Figure 5-3).

(1) Bit Design. Rotary drill bits aredesigned to cut specific material types.Choose the drill bit based on theanticipated formation. Either drag orrotary bits are available at a drill site.Normally, you will use drag bits forbeginning a borehole in unconsolidatedoverburden materials. These bits are usedfor hard, medium, and soft rock and arepart of the drilling-rig equipment. Whendrilling in soft rock, use a mediumsoft-rock drill bit. In very hard rock, stopmud rotary drilling; install casing to therock layers, use a down-hole air hammer.The objective is to produce a hole quicklyand efficiently. Be careful that you do not

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penetrate too quickly. Producing cuttings faster than you can remove them can cause seriousproblems, such as the drill string sticking in the hole, excessive completion delays, and loss ofequipment and the hole.

(2) Weight on Bit. Adding weight on the bit increases the torque required for rotation. Toomuch weight can cause excessive penetration and produce cuttings that are too large and heavy.Large cuttings are difficult to wash out and may cause gumming and premature failure of the bit.Insufficient weight reduces or stops penetration and can produce fine cuttings. In cohesive soils,fine cuttings may thicken the drilling fluid and fail to settle in the mud pit. How weight is appliedcan also cause serious alignment problems and difficulty in well construction. Rotary-drilledboreholes spiral slightly and are seldom straight. Once spindling occurs, weight added by pullingdown with the drill rig bends the string and magnifies the deviation. You should never use the chainpulldown to advance the hole beyond the first run (20 feet). Ideally, keep the drill string in tension.Add drill collars (heavy wall drill steel) at the bottom just above the bit. See Table 5-3 for drillcollar weights.

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CAUTIONUse the pulldown feature on the drill rig as alast resort for short distances in hard strata.

Bit weight required to cut rock depends on the design of the bit and the strength of the rock.Roller bits need a minimum of 2,000 psi of bit diameter for soft rock and shale and a maximum of6,000 psi of bit diameter for hard rock. Before drilling, add drill collars instead of drill pipe untilthe load is sufficient for reasonable cutting. As you dig deeper and add drill pipe, you may have tohold back on the drill string. See Table 5-4 for weight on bit and rotary speed.

(3) Drill Steel. Drill rods, collars, stabilize, subs, and bits are available in different sizes andmaterials. In most drilling systems, drill rods are either steel or aluminum and come in lengths ofeither 5 or 20 feet.

(4) Rotation Speed. Rotation speed is determined by the weight on the bit and the materialbeing drilled. Try to regulate the speed to produce the correct size cuttings. Experience will helpyou determine and regulate rotation speed.

(5) Fluid Requirements. Fluid requirements depend on size, weight, nature of cuttings, andcirculation velocity. Velocity depends on capacity and condition of the mud pump, annular area inthe borehole, and the stability and permeability of the formation. See paragraph 5-1e (page 5-8) formore information on drilling fluids.

Use the following calculation and Figure 5-4 (page 5-8) to estimate the mud-pump output andvelocity and the hole size requirements:

V = ( D 2- d 2)2

where—

V = velocity, in GPM.D = hole diameter or bit size, in inches.d = drill steel or drill collar diameter, in inches.

(6) Circulation Pressure and Velocity. These elements of the drilling fluid are controlled bythe pump capacity and speed. The fluid’s density, velocity, and viscosity let it carry cuttings. Ifthe drilling fluid is too thick, cuttings will not settle in the mud pit. Sufficient velocity with a fluidof low viscosity (even water) will carry drill cuttings to the surface. Excessive velocity will erodethe wall of the hole to the extent of failure.

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Pump pressure results from flow resistance caused byviscosity, friction, weight of the fluid column, orrestrictions in the circulating system. Pressure should beexerted at the ports in the bit, causing a downward jettingas the fluid exits. Regulate mud-pump pressure byvarying the RPM of the pump. Mud-pump pressureagainst the bit is not harmful if it does not exceed theoperating pressure of the pump. Other sources of fluidpressure can be detrimental. Pressure from friction occursif the drill string is long for its inside diameter or pipes areinternally upset. Frictional pressure increases wear in thepump. Pressure from the weight of the fluid column inthe annulus or from a restriction in the annulus caused byan accumulation of cuttings indicates insufficientcleaning. This type of pressure can cause formationdamage, resulting in lost circulation and wall damage.

(7) Stabilizers. Unless the drill string includesstabilizers (Figure 5-5) for large drill bits, drill a pilot hole,using drill collars as stabilizers. The initial pilot hole (6-to 7 1/8-inch diameter) will be straighter and easier tosample. The location of aquifers will also be easier todetermine. Use a larger bit to ream the hole to the desiredsize. Use overreaming bits, if available, because theyfollow the pilot hole best.

e. Drilling Fluids. Drilling fluid is circulated inrotary drilling to cool, clean, and lubricate the drill string,to flush cuttings from the hole, and to stabilize theborehole wall. Water is the basic fluid and is satisfactoryfor lubricating and cooling the tools. However, water haslimited abilities to carry cuttings and stabilize the boreholewall. Many drilling fluid additives are prepared andformulated for various purposes. Polymer fluids andwater-based clay fluids (muds) are the primary additivesused in water-well drilling. Table 5-5 lists drilling fluids.

Mud cools and lubricates through heat absorptionfrom the bit and reduction of drill-string abrasion againstthe borehole wall. Heat is generated as the bit scrapes andgrinds. Without the cooling fluid, the bit would overheatand be useless. Research indicates that removing thecuttings around and under the bit is the most importantfactor in keeping the bit cool. Requirements for coolingfluid are less than those for removing the cuttings.

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Therefore, if you keep the borehole clean with the fluid as you drill, you also cool and lubricate.This is true with clay muds and polymer fluids. Clay muds are colloidal suspensions. Solutionsare chemical mixtures that cannot be separated by simple filtering. Suspensions are physicalmixtures of solids and liquid that can be separated by filtering. This distinction underlies thedifference in behavior between drilling polymers (solutions) and drilling muds (suspensions). Youcan mix natural clays with water for use as a drilling mud. Drillers often use water in shallow clayey

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strata and depend on the formation clay to produce a suitable mud. Natural-clay mud properties aremarginal for good water-well drilling.

Hydrostatic pressure allows the fluid to support the borehole wall and is a function of the densityor weight of the mud column. Important characteristics of a drilling mud are viscosity and weightto carry cuttings, gel strength, yield point, and active clay solids for filter cake. Use the followingformula to calculate hydrostatic pressure:

where—

For example, the hydrostatic pressure of a 200-foot hole with a mud weight of 9 pounds is asfollows: 9 ft x 200 ft x 0.052 = 93.6 psi.

(1) Polymers. Polymer fluids are water-based and very low in solids. The polymer admixturecan be organic, inorganic, natural, synthetic ors synthetically formulated natural polymers. Polymeradditives are formulated for various drilling-fluid purposes and can be used alone or to enhance claymuds. Polymers, containing salt and other contaminants, are available and are compatible withwater. Polymers are more sensitive to pH than are bentonite muds. Change the pH to effect desirablechanges in the polymer fluid. Drilling-fluid weight impacts drilling rate and high-density drillingfluid reduces drilling rote. There is strong indication that the solids of a fluid have a similar effectas density. Polymer fluids are very different from clay muds because a large part of the polymer issoluble in water and becomes a solution when mixed with water. Long, complicated molecularchains tie up the water and can build viscosity without solids. In water-well drilling, many polymersare manufactured for producing drilling fluids, such as E-Z Mud, Revert, and Poly-Sal. E-Z Mudis a synthetic, inorganic polymer. Revert is a natural, organic polymer fluid derived from the guarplant.

Polymers are generally best mixed through a mud gun. Polymers used for special purposes areavailable from the manufacture complete with specifics on how to use the product. Most polymerscan hydrate more water than a high-grade bentonite. Up to ten times more bentonite is needed tobuild the same viscosity in a given amount of fluid, depending on the quality of the polymer. Apolymer does not fully hydrate as quickly as bentonite. Mix the polymer very slowly through themud gun a minimum of four hours before using for more complete hydration. The fluid will thickenas hydration continues, so do not mix to the desired viscosity. Some polymers possess physicalqualities that can result in unusual hydration, gelling and viscosity. Follow the manufacturer’srecommendations for hydration. Factors that affect the viscosity are quality of polymer,concentration and size of colloid, metallic ions in mixing water, temperature, rate of shear, and pH.

Water is the primary building block for drilling fluids. Water quality affects the overallperformance of drilling fluids. The action of bentonite in water is seriously impaired by dissolvedacids or salty substances. Acidic water usually contains dissolved metals that cannot be used unlesstreated. Hard water affects the suspending and sealing qualities of bentonite. You can test the pHlevel by using paper pH strips. The pH level should be 8 to 9. If the water is too acidic, treat it with

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soda ash at a ratio of 1 to 5 pounds of soda ash per 100 gallons of water. Following treatment, retestthe pH level as before.

Do not use water from wetlands, swamps, or small ponds for mixing drilling fluids because thewater may be contaminated. If you use water from these sources, chlorinate the water before makingthe drilling fluid. Be careful because chlorine removes metallic ions that are necessary for viscosityin polymers. Adjust the pH of drilling water to 7.5.

Temperature affects the viscosity and stability of some polymers. Consider the followingexamples:

Seven pounds of Revert per 100 gallons of water at 45°F yields Marsh funnel viscosityof 125 seconds per quart. The same mix at 85°F yields 70 seconds per quart.A 0.87 weight mix of Revert at 68°F yields a viscosity above 90 seconds per quart forthree and a half days. The same mix at 80°F maintains viscosity of 80 seconds per quartfor only two days.

Polymer drilling fluids can break down viscosity. Without treatment, the viscosity of somepolymers (Revert) completely breaks down in one to six days depending mainly on temperature.You can correct this by adding chlorine. Revert requires Fast Break; E-Z Mud needs sodiumhypochlorite at a ratio of 2 quarts for every 100 gallons of water. Other polymers, such as E-Z Mudand Poly-Sal, maintain their viscosity for long periods of time since natural breakdown is notsignificant. Table 5-6 (page 5-12) lists additives for drilling fluids.

Polymer drilling fluids have virtually no gel strength because the colloids are nonionic andexhibit no attraction for each other. Most of the drill cuttings should be washed out of the boreholebefore circulation is stopped. A polymer fluid does not have thixotropic properties to hold cuttingsin suspension. Shakers, desanders, or desilters are not needed when using polymer fluids. Sincemost of the cuttings are dropped out, friction and wear in the pump are minimized and the drillingrate is not impeded by cuttings or high density. A major advantage of polymers is the lack ofmechanical wear to the drill-rig mud system.

Some drilled fines (clay, silt) circulate back down the hole. Recirculated solids are much lessa problem with polymer fluids than with clay fluids. Revert will not hydrate in water containingany appreciable amount of borate. However, Borax can be used to produce a gel plug in hydratedguar-gum polymer. With a pH of 7.5, the borate cress-links the polymeric chains and forms a strongthree-dirnensional molecular gel. If a strong gel plug is necessary to get through a lost circulationzone, mix 1 cup of borax in 5 gallons of water and pour slowly into the pump section while pumpingat idle speed. When the berated fluid (stringy gelled mass) recirculates, stop pumping for one-halfhour. Resuming normal drilling should be possible after wasting the borated fluid. Repeat theprocedure, if necessary. Although the polymer fluid is not thixotropic and has no gel strength, itthins somewhat while being pumped.

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Polymer fluids build a type of membrane on the wall different from clay mud. Unnatural clayparticles (bentonite) are not introduced into the hole. Since the polymer fluid is partly a thicksolution, infiltration into the permeable wall is reduced. However, insoluble portions of somepolymer colloids do exist. The insoluble and cuttings are surrounded with thick coatings that aremore impermeable per unit thickness than a bentonite filter cake. The insoluble and cuttings sealthe wall of the hole with a thinner, less active layer. The impermeable layer performs the samefunction as the filter cake in clay muds but does not restrict the annulus.

The colloids in the polymer fluid are nonionic, have no chemical interaction, and are easier toremove in water-well development. When the viscosity of the fluid is broken, much of the cohesivefunction of the thin film becomes a water-like liquid and is washed out of the water well. Fieldtesting of polymer fluids, using the falter press and the Marsh funnel, yields different results. Themud balance for measuring fluid density does not change. Weighing of the polymer fluid is limited.You can add sodium chloride to the fluid to bring the weight up to about 10 pounds per gallon. Theaddition of heavy solids (ground barite) is ineffective because of the polymer fluid’s lack ofthixotropic qualities.

(2) Mud Products. Commercially processed clays for drilling are bentonite and attapulgite.Bentonite is superior except in brackish or salty water. (Use attapulgite in these waters.) Bentoniteforms naturally from decomposition of volcanic ash when ground. Bentonite consists of aggregatesof flat platelets in face-to-face contact. Bentonite is mined in many states, but the best grade(Wyoming bentonite) is mined only in Wyoming and South Dakota. Wyoming bentonite containssodium montmorillonite (the active part of the clay mineral) and is small in size, which is importantin building viscosity.

Mud drilling fluids should be mixed with a mud gun. When agitated and sheared with water,the bentonite platelets absorb more than 25 times their own weight in water, separate, and swell.The amount of surface area wetted determines the ability of the particle to build viscosity. Oneounce of Wyoming bentonite dispersed in water has more surface area than five football fields.Interparticle activity between platelets gives the mud its gel properties. The chemical compositionof the mixing water affects the ability of bentonite to develop desirable qualities. These qualitiescan be manipulated by adding small amounts of various chemicals.

(3) Mud Viscosity. True viscosity is a term relating only to true (Newtonian) fluids, such aswater, and is a proportional constant between shear stress and shear rate in laminar flow. Drillingmuds act differently in that the proportion between shear stress and shear rate is reduced when shearrate is increased. Drilling muds are thixotropic. The viscosity of a drilling mud refers to thethickness of the mud while flowing. Gel strength is the term used to describe the thickness of drillingmud at rest. Gel strength develops over a short period of time.

Yield point is the mud quality broadly included in viscosity. You need more stress (pumppressure) to cause the gelled drilling mud to start flowing than to sustain flow once the gel is broken.The stress required to initiate shear or flow is the gel strength of the mud. The stress required tomaintain shear is the viscosity. You want a higher yield strength with respect to the gel strength sothe mud becomes very thin in flow shear.

The primary function of viscosity is to help lift drill cuttings from the borehole. Other mudcharacteristics affecting lifting capacity are density, velocity, and flow patterns. Gel strength holds

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the cuttings in suspension at the bottom of the hole when circulation is stopped. The stress (hydraulicpressure) required to break the gel strength to initiate cumulation can be detrimental. Requiredbottom-hole pressures can cause fracturing or opening of fractures in the formation, resulting in lossof drilling fluid, formation damage, and borehole wall damage. Down-hole pressure required tocontinue circulation depends on friction, density (or weight of fluid column), and viscosity of themobilized fluid. These pressures can also cause serious problems. Therefore, it is desirable to usea drilling mud of relatively low density and viscosity, moderate gel strength, and high yield pointrelative to the gel strength (a very thin fluid in circulation).

(4) Mud Testing. The Marsh funnel (Figure 5-6) is routinely used to give an indication ofthickness or apparent viscosity of drilling fluid. The Marsh funnel is 12 inches long and 6 inchesin diameter and has a No. 12 mesh strainer and a 1,000-milliliter (ml) cone. The funnel has a 2-inch-long, calibrated, hard-rubber orifice with an inside diameter of 3/16 inch. The funnel’s cup ismarked with a capacity of 1,000 ml. Use the following procedure for the Baroid Marsh funnel:

Hold or mount the funnel in an upright position, and place a finger over the hole.Pour the test sample, freshly taken from the mud system, through the string in the top ofthe funnel until the level touches the top of the screen.Immediately remove the finger from the outlet tube, and measure the number of secondsfor a quart of mud to flow into the measuring cup.Record time in seconds as funnel viscosity.

NOTE: Calibration time for fresh water at 70°F is 26 seconds.

The funnel viscosity measurement obtained is influenced considerably by the gelationrate of the mud sample and its density. Because of these variations, the viscosity valuesobtained with the Marsh funnel cannot be correlated directly with other types ofviscometers and/or rheometers. Graduated in cubic centimeters (cc) and fluid ounces,the 1,000-cc measuring cup is designed specifically for use with the Baroid Marsh funnelviscometer. A quart volume is clearly marked on the measuring cup.

The desired mud consistency depends on many factors. Thenature of the formations will dictate mud qualities. However, youwill not know all the conditions before you start to drill. Theinexperienced driller must be careful because mud with the correctthickness often is too thin. You can adjust the viscosity by addingwater or clay. A good range for drilling muds is 32 to 50 secondsper quart. Viscosity is influenced by mud density, hole size,pumping rate, drilling rate, pressure requirements, and geology.Considering the thixotropic qualities of drilling mud, a funnelviscosity of 100 seconds per quart may be no more viscous thana funnel viscosity of 50 seconds per quart if both fluids are inmotion.

You can use test readings as an indicator of changes in mudthat might lead to problems. Therefore, conduct Marsh-funneltests before beginning operations and record the findings. Take

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mud samples for each test from the same location in the circulating system just before returning tothe hole. The apparent viscosity of the drilling mud in motion affects carrying capacity, the pumppressure (hydrostatic down-hole pressure) required for circulation, and the ability to drop cuttingsin the settling pit. These characteristics are also intrinsically involved with well hydraulics, densityof mud, density and size of cuttings, and particle slip.

(5) Density. The carrying capacity of a mud is affected by its density and the density of thedrill cuttings. If the cuttings are denser than the fluid, they will descend. The magnitude of thedifference in density, particle size, and fluid viscosity affect the rate at which a particle descends.Particle slip denotes this downward movement through the fluid. Ignoring thixotropy, the actualdownward particle slip is constant regardless of velocity of flow. However, when the upwardvelocity of fluid exceeds the downward particle slip, the new movement of the particle is upward.Up-hole velocity plays a major role in determining the carrying capacity of the cumulating fluid.The practical limits of up-hole velocity depend on pump size and capacity, inside diameter (ID) ofthe drill string, jet size in the bit, viscosity of the fluid, cross-sectional area of the annulus, andstability of the borehole wall. Up-hole velocity is not as simple as the comparison of pump capacity,drill string ID, and annulus. Up-hole velocity is not a constant.

The density of the drill fluid serves other purposesin rotary drilling. Heavy fluids can control (holddown) formation pressures encountered in drilling.You can build heavy mud by adding a weighingmaterial such as ground barite (specific gravity 4.25).Prepare drilling mud in excess of 20 pounds per gallonby using barite. First, mix bentonite and water to buildviscosity. Then, add finely ground barite so the mudwill hold the barite in suspension. Use heavy drillingmud only when absolutely necessary to controlpressures since the muds have disadvantages.High-density mud increases pressure on the formationby the weight of the fluid column. Figure 5-7 showsthe nomograph for determining the hydrostatic headproduced by drilling fluids. The increased pressure isfurther increased by the pump pressure required tomobilize the fluid in circulation. The increasedpressure can cause formation damage and loss ofcirculation. In formations that are strong enough towithstand the pressures without being damaged, thedrilling operation can still suffer.

The pressures from the mud and the formationshould be balanced so that the borehole bottomexposed to the drill bit is near surface eruption frompore pressure. That balance makes the formation easyto fracture and enhances the cutting rate. If the mudpressure is much lower than the formation pressure,the borehole can be unstable. If the mud pressure far

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exceeds the formation pressure, the cuttings may be suppressed and reground by the bit. The resultof recutting reduces bit life and lowers drilling rate. Mud density is increased by drill cuttings; themud rising in the hole is heavier than the mud returning to the hole.

All cuttings should be removed from the drilling mud in the settling pits and not recirculated.Although 100 percent removal is unrealistic, well-designed mud pits and mechanical screens,desanders, and desilters materially aid in removing cuttings from the mud. Water weighs 8.34pounds per gallon. Clean, low-solid bentonite mud can weigh 8.5 to 9.0 pounds per gallon; try tomaintain that weight. Increasing density of the mud during drilling indicates that the mud containsnative solids. The drill’s penetration rate could be exceeding the combined effort of the mud pit,desanders, and fluids to effectively separate solids from the drilling mud. To correct this problem,slow down the penetration rate and run the desanders to remove the solids.

You can determine the density or weight of the drilling mud using a mud balance. Fill the mud-balance cup with mud, and place the inset lid in the cup. Excess mud will be displaced through ahole in the lid. Clean the outside cup area, place the assembly on the center pivot, and balance itusing sliding weight. You read mud density as pounds per gallon and pounds per cubic feet. If youknow the mud weight that enters and exits the drill hole, you can evaluate the efficiency of the mudpit and mechanical separators, determine when to clean the mud pit, and tell how well the mud iscleaning the hole. If you take samples from only one location, take them from the return end of thepit.

(6) Filter Cake. Filter cake consists of solids from the drilling mud deposited on the boreholewall as the water phase is lost into the formation. Desirable properties are thinness andimpermeability. Drilling mud is a colloidal suspension that can be separated by simple filtering.With the hole kept full of mud, the hydrostatic pressure inside usually exceeds the formationpressure. Occasionally, an artisan aquifer is penetrated, with formation pressure higher than thehydrostatic in-hole pressure. When the borehole pressure is higher than the formation pressure, thedrilling mud tends to penetrate more permeable formations. Solids from the mud filter out anddeposit on the wall, and the liquid phase of the mud (filtrate) enters the formation.

Filter cake can be compacted against the wall by the excess hydrostatic pressure in the borehole.If the drilling mud is a well-conditioned bentonite and water mixture, most of the solids plasteredagainst the wall will be flat platelets of highly active clay. The filter cake is self-regulating basedon its degree of impermeability. As long as filtrate can pass through, the filter cake continues tothicken. A thick cake detrimentally increases down-hole cumulating pressure by restricting theannulus, making it difficult to pull the drill string because of the physical size of the drill collarsand bit. In deep and somewhat deviated holes, the danger of key seating increases. Because a thickfiltercake is of a lower quality and depends on its thickness to be effective, it is more easily damagedand eroded. A thick filter cake may indicate that the fluid has a high percentage of native solids.You may have to clean these solids from the mud before drilling progresses.

A thin, highly impermeable filter cake bonds well to the wall and provides a surface for thehydrostatic pressures to act against to support the wall. Filtrate loss into the formation can accountfor significant fluid loss, if the consistency of the drilling mud is not good. Good consistency doesnot necessarily mean thick; it has to do with the bentonite content and the quality of falter cake. Ifa permeable formation is encountered with pore spaces too large to be plugged by the fine bentoniteparticles, the drilling mud will enter the formation. That mud loss can take the entire output of the

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mud pump. The drill cuttings being carried up the annulus can sometimes be beneficial. Thecuttings are coarser than the bentonite particles and may help bridge across formation pores. If youuse this technique, maintain the normal drilling rate to supply the cuttings. Slow down the pumpingrate to reduce pressure on the formation while bridging the open spaces. With sufficient bridging,a suitable filter cake follows, circulation is regained, and normal drilling operations are resumed.

In the field, you can test the filtration properties and filter-cake thickness using the filter-presskit. This kit consists of a press with a mounted pressure gauge and a CO2 charging system that isused to simulate the hydrostatic pressure inside a 200-foot hole. By placing a sample of drillingmud in the press and charging the system, you can forma filter cake. The filter cake should be lessthan 2/32-inch thick.

(7) Salty Environment. A high chloride content in the mixing water causes bentonite to reactanomalously or not react at all. The ground bentonite remains agitated; it does not disperse, hydrate,or swell. In salt water, bentonite is an inefficient clay additive for drilling mud. The dissolved saltis an electrolyte that changes the interparticle activity of bentonite. If you add sufficient amountsof salt water to a fresh water and bentonite mud mixture, the dispersed platelets will form lumps.Viscosity and filtrate loss increase and the mud’s ability to build a thin, impermeable filter cakedecreases.

Attapulgite is often used for salty formations. The small particles produce a highsurface-area-to-volume relationship and good viscosity building. Unlike bentonite, the particleshape is needle-like. Viscosity building in attapulgite depends on the entanglement of these needles.The disorderly arrangement of the particles accounts for the poor filtration qualities of attapulgite.The filter cake is more like a layer of strew or sticks. Attapulgite clay does not have the physicalqualities to build a thin, impermeable filter cake. If you can mix bentonite in fresh water first andthen add salt water as make-up water, the bentonite flocculates; that flocculation can be reversedby chemical treatment.

(8) Well Hydraulics. You must have a basic understanding of well hydraulics. Fluid is pumpeddown the drill string, out the ports in the bit, and up the annular space between the drill string andthe wall. The fluid empties into the mud pit, through any mechanical solids separating equipment,and is picked up from the pit by the mud pump for recirculation. The system is intended as aconservation system. Except for mud lost into the formation or where artisan water exceedinghydrostatic pressure flows into the hole, the return is largely complete and the mud-pit level doesnot change. Even if thes system is in equilibrium, you need to understand the up-hole rearrangementof flow patterns.

Fluids flow in two distinct patterns. Laminar flow is orderly. The streamlines remain distinctand the flow direction at every point remains unchanged with time. Turbulent flow is disorderly.The flow lines and directions are confined and heterogeneously mixed. The type of flow dependson the cross-sectional area of the fluid course and the velocity, density, and viscosity of the fluid.In water-well drilling, the cross-sectional area of the annulus is usually several times that of theinside diameter of the drill string. Because of the increase in volume in the annular space, flow atthe point the fluid leaves the bit is turbulent. The fluid becomes laminar flow when it begins flowingup the annular space. The returning fluid velocity is slower and the drill fluid is more dense andprobably has more apparent viscosity, which affects the flow pattern. To clean the hole and carrythe drill cuttings out, turbulent flow in the annulus would be better.

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Picture the flow in the annulus as a series of nested tubes. Velocity varies as if these tubes weresliding past one another while moving in the same direction. Flow near the wall and near the drillstring is at a slower rate than near the center. Cuttings near the center can be vigorously lifted whilecuttings near the wall and drill string actually slip in a net fall. Rotation of the drill string changesthe flow pattern near the drill string and materially enhances particle lift.

For example, if you use a 3 1/2-inch ID and 4-inch outside diameter (OD) pipe to drill a 9-inchhole and pump 200 GPM, the velocity of the ID pipe is 400 feet per minute (fpm) and the velocityof the OD pipe is 75 fpm. To test cumulation at these rates (bit is 300 feet deep), pump down amarker (strew or oats). The majority of the material should take 4 minutes and 45 seconds to return(300 feet at 400 fpm takes 45 seconds and 300 feet at 75 fpm takes 4 minutes). To clean all thecuttings from a 300-foot depth with an average up-hole mud velocity of 75 fpm will require morethan four minutes of pumping. Consider this concept regarding sampling cuttings from the returnmud.

If cuttings remain in the annular space between the drill rod and borehole wall when circulationis stopped, they will produce a denser fluid than the clean drilling mud inside the drill rods. Thedenser mud in the annular space will then flow down the hole and force the clean drilling mud upthe drill rods. This causes a geyser effect, and the drilling mud may shoot several feet into the airuntil the mud columns equalize. (Some drillers mistake this for a caving hole.) If this situationhappens when adding drill rods, the circulation time should be increased after drilling down thenext rod. Use the following formula to calculate the annular space volume

where—V = annular space volume, in cubic feet.D = hole diameter or bit size, in inches (Figure 5-4, page 5-8)d = drill hole or drill steel collar diameter, in inches (Figure 5-4, page 5-8)L = hole length, in feet (Figure 5-4, page 5-8)

(9) Mud Pits. Rotary chilling preparation is the design and excavation of an in-ground mudpit or installation of a portable mud pit and the mixing of the drilling fluid. For standard drillingoperations that use well-completion kits, well depths could range from 600 to 1,500 feet. For wellsup to 600 feet using the 600-foot WDS, use portable mud pits. For wells over 600 feet, use dugmud pits. In either case, you will have to clean cuttings from the pits as drilling progresses. Designconsiderations include the anticipated depth and diameter of the drill hole, since the material cuttingsfrom the hole will be deposited in the mud pits.

The volume of the pits must equal the volume of the completed hole. Therefore, during drilling,you will have to clean the cuttings from the pits frequently. If you have a backhoe to dig and cleanthe pits, size and depth of the pits are not critical. If you must dig and clean the pits with shovels,width and depth are important. Drilled cuttings should drop out of suspension in the mud pit.Therefore, long, narrow pits are better. Figure 5-8 shows a mud-pit layout and a chart depictingmud pit capacities and dimensions.

NOTE: Portable mud pits will require constant cleaning.

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Mud pits are part of the circulating system for mixing and storing drilling fluid and for settlingcuttings. The ground slope will affect site layout. Pit design can enhance pit performance. Mostdrillers agree&t using multiple pits is best when dropping drill cuttings from the fluid. The volumeof the pit should be one and one-half to three times the volume of the hole. This will provide fluidto fill the hole and an excess volume to allow stilling and settlement or processing before returningto the drill string. A volume of three times the hole volume will minimize drilling-fluid and mud-pitmaintenance. Figure 5-9 (page 5-20) shows a mud pit that is prepared on-site. Figure 5-10 (page5-20) shows a portable mud pit.

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If drilling mud is processed through shale shakers, desanders, desilters, and space and time forcuttings settlement are not important, long, narrow pits connected at opposite ends by narrow,shallow trenches are preferred. If using a polymer fluid that has no thixotropic qualities, thesettlement of cuttings is a function of time at low velocity or no flow. With polymer fluid, along-path mud pit is ideal; if part of the flow almost stops, cutting settlement is enhanced.

If you use a clay-based mud with thixotropic qualities and the mud moves slowly or flow stops,the gel strength can hold the cuttings. High velocity through narrow, shallow trenches holds thecuttings in suspension. If mud runs over one or more wide baffles or weirs, flow shear and velocityare low. These factors enhance cuttings to drop out. If mud processing equipment is available, useit. Recirculating clean fluid reduces power requirements, wear, and erosion and enhances drillingrate. See Figure 5-11 and Figure 5-12 (page 5-22) to calculate weir dimensions and volume.

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f. Rotary Drilling Problems. Some problems in rotary drilling are minor and others are seriousand can result in failure to complete a hole or even loss of equipment. Many serious problems startminor but can become serious if not recognized or handled properly. For example, in a loose sandzone, the borehole walls can slough and cause drilling fluid loss. By reducing or increasing fluidvelocity, you can stabilize the wall and regain fluid circulation. However, if you do not recognizethe condition and you continue drilling, the wall will slough and create a cavity. The cuttings losevelocity, become suspended in the cavity, and tend to fall back into the hole when you add a rod.This action can result in the rods or the bit becoming stuck in the hole. Other problems can resultfrom subtle changes in geology, imbalances in the drilling operation, or equipment failure.

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(1) Lost Circulation. Lost circulation refers to a loss in volume of drilling fluid returning tothe surface. The implication is that some fluid pumped down the drill pipe is entering the formations.The mud pit will lower, since some of the mud is used in forming a mud cake on the borehole wall;however, increased lowering can indicate circulation loss. Losses can occur through open-gradedsand or gravel or open joints in rock. A loss can occur when cuttings are not washed out and theborehole annulus becomes restricted, resulting in increased down-hole pressure. Spudding (raisingand lowering the drill string) the hole too violently can cause loss. Spudding helps wash cuttings,but down-hole pressures increase momentarily. Experienced drillers can estimate when spuddingis safe. When fluid cumulation is lost and a driller continues to drill, he is drilling blind. Anexperienced driller that knows the rig can often drill blind successfully, but reestablishing circulationis always safer.

Reestablishing circulation can involve several techniques. You can add commercial items suchas chopped paper, straw, cottonseed, and nut hulls to the mud pit. Sometimes, while the loss zoneis grouted and redrilled, the grout is lost into the formation. In this situation, you may have to setcasing through the loss zone. Occasionally, reducing fluid velocity while continuing to drill willplug the loss zone with drill cuttings. Reestablishing circulation is usually a trial-and-error process.The longer you drill without circulation the more difficult it will be to reestablish circulation.

(2) Fall-In. Fall-in is material that accumulates in the bottom of the borehole after you stopcumulation. This material is borehole-wall material that results from sloughing or caving or cuttingspreviously carried in suspension. Fall-in occurs when you encounter a loose, unstable formationand the drilling-fluid weight is insufficient to stabilize the formation. If you anticipate or suspectfall-in, raise the drill bit off the bottom of the hole (20-foot minimum) each time drilling isinterrupted. This will prevent the cuttings and fall-in from settling back around the bit until theproblem is solved.

(3) Stuck Drill String. The drill bit and any collars just above the bit are larger in diameterthan the drill pipe. The string becomes stuck when cuttings collect on the bit and collar shoulder.This condition is called sanded in. Be careful because you can break the drill pipe while trying toremove the drill string. Regaining circulation and working the sand out are seldom successful. Ifthe formation will not take the fluid when you engage the pump clutch, the relief (pop-off) valvewill operate to relieve the pressure. Little can be done to free the drill string except to wash a smallpipe down the annulus to the bit and jet the settled sand back into suspension. When the annulusis too small to pass a jet pipe, a part of the drill string may be lost.

When the annulus is small, excessive up-hole velocity can promote erosion of the filter cakein granular zones and allow caving against the drill pipe. If this occurs, try to maintain circulationand rotation, even if circulation is slight. Where the grains are angular, the drill pipe can becomelocked while being rotated. This situation is similar to a sanded-in bit. With smooth pipe (notupset), hammering up and down will sometimes dislodge the string. You can reestablish circulation

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and continue drilling. Be careful because hammering up and down can produce unfavorablecompacting of the sand. In a hole of fine-grained soil or shale, where the alignment has significantlydeviated and the drill pipe has wallowed into the wall, the pipe can become wall stuck. Pipe frictionand relatively high borehole pressure can move the pipe tighter into the wallowed groove as youpull the string. An alert driller should recognize early stages of deviation and take measures torealign the hole.

(4) String Failure. When the drill string parts, leaving a portion in the borehole, the drill stringis rung off. The portion in the borehole is a fish and attempts to retrieve the portion is fishing.Fishing tools include a tapered tap and an overshot die (Figure 5-13). Ringing off is normally fatiguefailure in the drill-rod joints caused by excessive torque or thrust (repeated flexing and vibrationthat crystallizes heat-treated tool joints) or by borehole deviation (with flexing of the string).Examine drill rods for signs of failure.

(5) Deviation. A deviated borehole is called goingcrooked. If you make the initial setup without plumbing thekelly, you can expect the borehole to go crooked. A crookedborehole usually amplifies other problems and can make aborehole unsuitable for a well. You should always anticipatedeviation, since the borehole naturally tends to spiral frombit rotation. Variations in the formation badness may startdeviation. Excessive bit load magnifies minor initialdeviation. Use all available guides and collars and areduction in bit load to minimize deviation.

(6) Swelling Soil. The in-hole effects of swelling soil(shale or clay) that absorbs water from the drilling fluid issqueezing. The result is a borehole that is undergauged tothe extent that you cannot pull the bit by normal hoistingmethods. In such cases, you can cut back through theblockage with a roller rock-bit or a drag bit. Swelling cancause caving and failure of the wall. Keep water out of the

formation to prevent swelling. Special polymer drilling fluid additives that limit water absorptionare available. High quality bentonite forms a thin but highly impermeable filter cake.

5-2. Air Rotary Drilling. Air rotary drilling is similar to mud rotary drilling except that the fluidcirculated is compressed air. The air is not recirculated. Using compressed air is advantageouswhen water for drilling is inconvenient, fluid is being lost to the formation while drilling, or youhave difficulty washing sticky clay formations from the hole. Also, air rotary drilling requires muchless development time. You may have to adjust air rotary techniques with each well you drill. Somedisadvantages to air rotary drilling are that air cannot support the wall of a hole in an unstableformation, changes in the return air flow are not as readily apparent as in mud flow, and air is notas effective in cooling and lubricating the drill bit and string.

a. Air Supply. Air has no density or viscosity, so cuttings are blown out of the hole at highvelocity. The up-hole air flow is turbulent and more effective in lifting the cuttings. The lack ofdensity and viscosity increases the particle slip so a continuous and high velocity up-hole flow mustbe maintained to keep the hole clean. An upward velocity of about 4,000 fpm is sufficient to clean

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cuttings out of the hole. Cutting removal also depends somewhat on size, density, and amount ofcuttings. Up-hole air velocity is computed by dividing the output volume of the air compressor, incfm, by the cross-sectional area of the annulus of the hole, in feet. Air compressors are rated on thefollowing items:

Intake air volume.Condition. Compressors wear with use, causing capacity to decrease.Sea level. Output volume capacity is reduced about 3.5 percent for every 1,000 feetabove sea level.Temperature. Efficiency is reduced when temperatures are above 60°F and is increasedwhen temperatures are below 60°F.Rotation speed. Output from the compressor is directly proportional to the motor’s RPM.Do not operate a compressor at lower RPM to reduce wear.

Dry material drilled by air will create a large amount of dust when blown from the borehole.Inject water to control the dust. Depending on the nature of the material drilled, the amount of watercould be 1/2 to 5 GPM. Water injection increases air density and improves carrying efficiency forthe cuttings. Adversely, water can cause the cuttings to stick together, making them heavier andharder to blow out of the borehole, or the cuttings may stick to the borehole wall, causingconstriction.

Minor wetting or dampening makes some walls more stable; excessive wetting can cause a wallto fail. Adjusting the amount of water injected into the borehole takes experience. Air has nowall-stabilizing qualities. In soils where sloughing and caving are a problem, injection of a thindrilling mud (bentonite mixed with the injection water) will control the dust and can contribute tostability.

In drilling large diameters (12 inches) with standard drill pipe (3 1/2 inches OD), the annulusequals 0.7 square feet. Using a 1,000-cfm compressor the up-hole velocity would be about 1,400fpm, which is not enough velocity to remove cuttings. While penetration will progress, the cuttingstend to stay at the bottom of the borehole under the drill bit and are recrushed. These cuttings actas a pad under the teeth of the bit and prevent proper cutting action. The compressor normallycannot drill holes by straight air rotary.

Use the following equations to estimate compressor size, up-hole velocity, and hole-sizerequirements for air drilling or Figure 5-14 (page 5-26) to determine up-hole velocity. Therecommended up-hole velocities are: 3,000 fpm, minimum; 4,000 fpm, fair; and 5,000 fpm, good.

where—

and

Vmin= ( D 2- d 2)16.5

Vmin

Dd

= minimum velocity, in cfm.= hole diameter or bit size, in inches (Figure 5-4, page 5-8).= drill steel or drill collar in diameter in inches (Figure 5-4, page 5-8).

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where—

VCVmin

= actual up-hole velocity, in fpm.= compressor capacity, in cfm.= minimum velociy, in cfm.

Air drilling has a depth limitation becauseof water in the borehole. Air pressure mustdisplace the head of water in the boreholebefore it can exit the bit. An advantage is thatwhen you encounter water, it. will dischargewith the air. As drilling progresses, you canestimate the amount of inflow to the well.When calculating the static head of water,remember that 0.434 psi equals 1 foot of heador 1 psi equals 2.3 feet of water. For example,the minimum psi required to overcome a400-foot static water-level column is 173.6 psi(400 ft x 4.34 psi= 173.6 psi).

b. Foamers. Commercial foamers fordrilling enhance the air’s ability to carrycuttings and reduce the velocity required to clean the borehole. The foamer is mixed with theinjection water but does not foam with gentle stirring; therefore, pumping is not hindered. Foammust be pumped at a pressure greater than the air-line pressure into which it will be injected. Thefoaming and mixing with air largely occurs when exiting the drill bit. If air flow is reduced fromthe volume required for air rotary drilling and the injection rate is tuned to the airflow, the foamleaves the hole as a slow-moving mass (Figure 5-15). The foam is laden with drill cuttings and theborehole is effectively cleaned with only 10 percent of the air volume required had foam not beenused. You can drill boreholes 2 feet or more in diameter with a well-tuned air-foam operation usingair compressors. See Table 5-7 for a list of common problems with air-foam systems.

Commercial foamers vary and come with mixing instructions on the container. You may needonly a few foamers to produce large volumes of rich foam. Less than one quart of foamer mixedwith 100 gallons of water injected at a 2- to 3-GPM rate is sufficient for a 12-inch diameter borehole.The column of foam provides slight stabilization to the wall. You can increase the richness anddensity of the foam by mixing bentonite with the injection water before adding the foamer. A verythin fluid of 15 to 20 pounds of bentonite mixed in 100 gallons of water is suitable for injection inair-foam drilling.

Adding foamer to this fluid in the same proportions as clear water, results in richer, more stablefoam. This technique is sometimes called air-foam-gel drilling. The gel refers to the bentonitefraction. Because of the increased richness, stability, and density of the air-foam gel, the air’scutting-carrying capacity and the wall stabilization are enhanced. Foam reaching the surface mustbe carried away from the drill rig to avoid mounding over the work area. Foam eventually dissipates

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when exposed to the atmosphere. Use eitherof the following methods to remove the foamfrom the rig area:

Method 1. Use a packer to seal thetop of the surface casing around thedrill pipe or kelly bar so eitherrotates freely. Fit the top of thesurface casing with a T below thepacker for connecting a waste pipe.As foam comes out of the wastepipe, remove it from the rig.Method 2. Place a T at the top ofthe casing with an air-line eductorthat causes a vacuum at the top ofthe hole. The foam is vacuumedinto and blown through the wastepipe. By using an eductor, you canobserve and regulate the returningfoam. The eductor is fabricatedand the drilling operation does notusually require the full output of thecompressor.

5-3. Percussion Drilling. This type of drilling involves crushing by impact of the teeth of the drillbit. Most percussion drills are actuated by compressed air (pneumatic percussion). Essentially,percussion drilling for water wells uses down-hole, pneumatic-percussion hammer drills. Downhole means the percussion motor (actuating device) is at the bottom of the drill string.

Percussion drills are best suited for drilling brittle, moderately soft to hard rock. In hard rockwith percussion drills, you can drill faster and more economically than with other drilling methods.The air blows the cuttings from under the bit and up the annulus to the surface. The air’s ability tocarry the rock chips depends primarily on high air velocity. An up-hole velocity of about 4,000

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fpm is required to remove cuttings. If drill penetration rates are high (30 fpm or more), you mayneed a higher up-hole velocity to clean the hole. To drill water wells with percussion drills, youneed to balance drill paragraphmeters to the materials to be drilled.

Down-hole hammer drilling with a large diameter hammer or bit (Figure 5-16) usually resultsin a very crooked hole unless you use drill stabilizers or drill the hole in two steps. For two-stagedrilling, drill a small pilot borehole with a 6- to 6 1/2-inch bit on a small hammer using drill collarsas stabilizers. Enlarge the borehole using a stinger bit for drilling. The Navy’s well-drilling packagecontains the stinger bit.

a. Equipment. Shallow holes for loading explosives inrock quarries and other excavations have been drilled bypercussion. Percussion drills are used because they penetratequickly, even through hard rock. Most percussive motors oractuating devices are above ground. Top-head percussiondrilling is not practical for deep boreholes because too muchenergy is lost in the long drill string. The down-hole drill wasdeveloped for efficiency. This drill is adaptable to most rigsand can drill water wells to depths exceeding 2,000 feet. Tooperate the drill, you hoist, handle, and rotate the drill stringand drill motor and have an adequate air supply. You cansupplement the air supply with an auxiliary (tag-along)compressor through simple plumbing. The 600-foot WDScomes equipped with auxiliary air connections.

During operation, an air-actuated piston impacts the drill-bit shank. Porting within the drill case forces the piston up and down with the full force of the airpressure. The drill-bit shank is splined and can slide in the splines about 2 inches until fully extended.The bit is held in the drill by a retainer ring and can have several design shapes. Currently, all down-hole bits are set with carbide buttons specifically formulated for the percussion application. Thecarbide button bit is more durable than other bits made from hardened steel. However, the drill bitdulls and buttons flatten from wear. A dull bit is less efficient, works harder, is easily damaged,and has a reduced production rate.

Flattened carbide buttons can be reshaped with a green stone. An experienced operatorrecognizes excessive wear and knows when to reshape the button. A percussion drill bit shoulddrill 1,000 feet or more in hard rock without reshaping. A properly maintained bit has the longestservice life and drills the most economical holes. Sharpening and reshaping the carbide buttons aredetailed procedures. See the manufacturer’s service manual for these procedures. The object ofreshaping the button is to restore the hemispherical shape without removing excessive carbidematerial. The cutting points on a reshaped bit will be about equal in length. The flat area of eachbutton is symmetrical around the cutting point and each button wears equally, which makesreshaping simple. Marking the center of the flat with ink represents the original cutting point andis the same length from the bit body as the other buttons. Carefully grind the worn button to a roundshape leaving a flat (1/16-inch diameter) at the ink mark. Grind each button consistently, realizingthat the reshaped buttons will not be perfect.

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b. Power. Operating the down-hole drill is not difficult. Percussion drills are designed tooperate at air pressures of 150 to 350 psi. The percussion drill is an orifice that leaks air out of thesystem. Air passing through the percussion drill actuates the piston and exhausts into the hole. Theair volume used to actuate the drill is consumed by the drill. As the air consumption of the percussiondrill increases, the air pressure delivered to the drill increases (Table 5-8). For example, if apercussion drill consumes 150 cfm of air at 200 psi, you will need a compressor that maintains 200psi while losing 150 cfm of air to drill at 200 psi.

Compressors are positive displacement air pumps. Pressure is a function of chamber ratio andleakage within the displacement mechanism. For example, a 200-psi compressor will produce 200psi in a closed receiver while turning a few RPM. The volume of air produced is a function of thedisplacement chamber, size of the cylinders or rotors, and the speed of rotation. Volume output isdirectly proportional to speed of rotation. Efficiency of the compressor is adversely affected bywear within the compressor and the elevation and ambient temperature.

Energy output from any drill is directly proportional to the air pressure delivered to the drill(Table 5-8). The percussion drill reacts to a pressure differential between intake and exhaust. Thepressure delivered to the drill is somewhat less than the gauge pressure at the compressor becauseof friction loss in the plumbing; pressure in the borehole increases with depth because of frictionand the load of cuttings and water. Increased pressure in the borehole reduces the effective pressuredifferential cross the drill. You can calculate friction losses in plumbing and pressure at the bottomof the hole, but the calculations are not very useful. When drilling, you can hear the hammeroperating in the hole when it reaches the bottom. If the hammer fails to start operating, do not letthe bit rotate on the bottom of the hole because you could destroy the buttons.

c. Procedure. Attach the percussion drill to the drill string or drill kelly and lower the drilluntil the drill sets on the material. Extend the drill bit (open position) in the splines. If you applyair with the drill bit extended, the air blows directly through the drill and the drill does not function(the piston is not actuated). Weight applied on the drill must be sufficient to push the drill bit intothe drill (closed position) and hold it closed. While maintaining the load, apply air pressure andslowly rotate the drill. When these actions are balanced, the drilling operation is optimal. Balanceis attained by experimenting during drilling.

(1) Weight on Bit. The weight applied to the drill must be sufficient to hold it in the closedposition while drilling. While the drill bit is splined and can move in relation to the drill, the bitshould not move in the splines while drilling. The required weight on the bit (bit load) variessomewhat with percussion drills from different manufacture. With a given drill, the bit load varieswith the air pressure used for drilling. The air pressure does not tend to enter the drill bit (open

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position) however, the energy with which the piston strikes the bit shank is directly proportionalto the air pressure applied. Consequently, you will need more bit load to keep the bit in the closedposition with higher air pressure. See the manufacturer’s manual for specific recommendations forminimum bit load. The range for a 6-inch drill generates about 2,500 pounds total bit load at 125psi to 4,000 pounds total bit load at 200 psi. Increasing bit load above the recommended minimumdoes little to increase the drilling rate. To achieve an increase in production rate, add weight if itdoes not adversely affect the rotation speed or constancy. Too much bit load will—

Affect the constancy of the rotation, which is detrimental to drilling production rate.Damage the drill.Cause excessive wear and premature failure of the bit.

(2) Plumbness. Water wells should be plumb and straight. Apply bit load by using drill collarsto hold the drill string in tension. Most rigs have a mechanism designed for that purpose. Becausethe drill string is relatively flexible, loads applied from the top will cause the drill string to flex andcan misalign the drill bit. This procedure can cause the drill to deviate from vertical. Continuedtop loading will exaggerate deviation. Apply bit load by adding heavy drill pipe sections (drillcollars) at the bottom of the drill string just above the bit. If you add a sufficient load at the bottom,you can hold the drill string in tension while drilling. The borehole tends to be straight because ofthe pendulum effect. Borehole deviations from vertical are sometimes associated with fast drillingrates. Such deviations actually result from crowding the bit (trying to increase the penetration rateby overloading the bit).

(3) Air Pressure. Exceeding the 350-psi rating of the drill is not possible with the suppliedcompressors. The energy output of the drill is proportional to the air pressure delivered. Try tooperate the drill at the maximum air pressure available. Lubricate the drill, using an in-line oilerdesigned for operation at the maximum anticipated working pressure. To control dust, inject a smallamount of water into the airline. The injection pump and plumbing can be extremely dangerous iffailure occurs because they are subjected to maximum pressure.

CAUTIONDo not exceed the maximum air-pressure

ratings of percussion drills.

WARNINGRapid expansion of compressed air from bursting

hoses and loose connections can cause injury.Only use replacement parts in the air system

that the appropriate TMs recommend.

(4) Rotation. As drilling progresses, adjust the bit rotation to the penetration rate. As the holedeepens, the bit should make one revolution equal to the length of exposure of the carbide buttonsin the bit (about 1/3 inch). The rule of thumb is that the rotation rate (in RPM) should about equalthe penetration rate in feet per hour. The rotation rate for percussion drilling is slower than forrotary drilling. For percussion drilling to function at maximum proficiency, the rotation must beconstant. As the piston strikes the bit shank (about 1,200 blows per minute at maximum air

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pressure), the constant rotation allows the bit buttons to chip continuously at new rock. If the rotationrate is not constant (stops and jumps), the buttons hammer several times atone place before jumpingto new rock. Erratic rotation produces variable sized chips, which are harder to clean from the hole.Erratic rotation also causes the buttons to penetrate too deep, increasing drag on rotation andexcessive wear and button breakage.

There are two main causes for erratic rotation. Top-head-drive rigs rotate the drill string witha hydraulic motor. Even though you can apply tremendous torque, a hydraulic system does notproduce positive movement but reacts to drag or resistance to drill string rotation. The hydraulictop-head-drive rig is highly susceptible to erratic rotation. The primary force resisting rotation isweight on the bit. If this weight is excessive, the hydraulic drive produces a series of pressurevariations and the bit rotates in a sequence of starts and stops. Even with mechanical drive rotation,which is nearly positive movement, dragon the drill bit will cause twist in the drill string, resultingin erratic rotation of the bit. This occurrence is more pronounced in deep holes.

The secondary cause of erratic rotation is borehole wall friction. You cannot eliminate allfriction between the borehole wall and the drill string. The more a borehole deviates from beingstraight, the greater the friction. It is easy to visualize a distorted drill string caused by excessivetop loading and how the distortion can cause increased borehole wall friction. Other contributorsto borehole wall frictional rock abusiveness, poor lubrication of the drill string (injected or natural-water condition), and poor cutting removal.

d. Adjusting to Variables. Economical and satisfactory drilling, using the down-holepercussion drill, requires fine tuning of the variables. Efficiency is directly proportional to the airpressure delivered to the drill. Operating at the maximum air pressure should be the constant. Thebit load, ideally a bottom string load, should exceed the maximum load required for the drill so theload can be properly adjusted by increasing hold back with the drill rig. Do not overload the bottomstring because the drill string weight increases as the depth increases. Do not overload the hoistingcapacity of the rig. Adjust the rotation speed to the penetration rate and use the constancy of therotation to regulate weight on the bit.

Air blows the rock chips from under the drill bit on up the annulus to the surface. Since air hasno effective viscosity or density to float the chips, removal is a function of the velocity of thereturning air. You will need a minimum velocity of 3,000 to 4,000 fpm. Larger diameter drill pipereduces the area of the annulus, which effectively increases the velocity of a fixed air volume. Ifyou cannot achieve the required up-hole velocity, add foam to help remove cuttings.

Effectively removing cuttings as drilling progresses is critical. When the drill bit is extendedin the splines to the open position, the maximum volume of air passes through the drill. Cuttingsmay not be removed efficiently from the hole, resulting in an accumulation of cuttings around thedrill. Accumulation may increase when compressor capacity is insufficient to maintain maximumpressure while drilling. This condition may be signaled by the drill sticking, which retardsdownward movement and affects bit load and drilling energy. The sound of the drill indicates thisproblem. Apparent change in the air return, cuttings returned from the annulus, and other indicatorslearned from experience also indicate an accumulation problem.

Detrimental effects of inefficient cutting removal include reduced penetration rate, damage tothe formation by fracturing, induced instability in the hole wall, damage to or even loss of drilling

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equipment, and loss of the borehole. Accumulation may be caused by insufficient drilling airvolume, a percussion drill not suited for the hole, a sudden influx of groundwater, or too rapid apenetration rate (large load of cuttings). The alert driller will sense a problem before it seriouslyaffects the operation. Keep the hole and blow out all cuttings before shutting off the air to addanother rod. By raising the drill slightly, the bit is extended in the splines (open piston), thepercussive action stops, drill bit penetration (production of cuttings) stops, and maximum air passesthrough the drill to clear cuttings from the borehole. The alert and efficient operator will use thistechnique as conditions dictate.

The down-hole percussion drill is designed to operate in extremely unfavorable conditions.The service life can be dependable with proper care. Lubricate the drill during operation. Use themanufacturer’s recommend injection of a minimum of one quart of rock drill oil during each hourof drilling. During drilling, the LP-12 is oiled with an in-line oiler plumbed into the drilling air line.Water injection into the air line is common and is not detrimental to the lubrication process. Drillrigs used for pneumatic drilling are equipped with a small, positive displacement pump (injectionpump). Injecting water is helpful because it reduces dust at the surface, improves cuttings removal,and stabilizes the borehole wall. A water injection of 2 to 5 GPM is satisfactory. Adjust injectionrates to the specific material drilled. Water injection improves lubrication of the drill string, providessome cooling of the compressed air and drill system, and is beneficial for rock drilling.

When you remove the drill from the borehole, break it down, inspect it, clean it, and repair it,as necessary. Oil all machined surfaces and lubricate threads with tool-joint compound beforereturning the drill to the borehole or to storage. Often a drill is left idle in the hole for an extendedperiod. If this occurs, lubricate the drill. Lift the drill off the bottom, close the water injection valve,blow air through the hammer, and add oil (1 to 2 quarts) to circulate and lubricate the surfaces.Reasonable service and care improve the life of the drill.

5-4. Reverse Circulation. Military well-drilling systems are not currently designed for reversecumulation drilling. In rotary drilling, the circulating fluid is pumped at high velocity down the drillstring and up the annulus. Weighty, thick building materials are dispersed in the fluid to help liftthe cuttings. You will need additives because the annulus area is greater than the cross-sectionalarea of the drill pipe, and the upward velocity in the annulus is much slower than the downwardvelocity inside the drill pipe. Additives help stabilize the borehole wall and keep it open. Withreverse circulation, fluid is sucked up the drill string at a high velocity and then moved down theannulus. The larger the annulus, the slower the descending velocity. This method of drilling isused primarily for large-diameter, shallow (over 300 feet) water wells in alluvial materials.

a. Advantages and Disadvantages. Reverse circulation is most effective in granular materialswith little cohesion. In cohesive soils, fluid will not clean the drill bit. The advantages of reversecirculation are—

Slow-moving fluid in the annulus--walls are less apt to erode.Additives--usually are not needed since the turbulence and high velocity inside the pipelift the cuttings.Borehole wall cake--is finely filtered and easily removed during well development.

The following lists disadvantages of reverse cumulation:

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Stability--depends on excess inside pressure acting against the borehole wall.Borehole wall--is not sealed by an effective filter cake.

Keep the borehole full and backed with a large water reserve to maintain an excess hydrostatichead. Make sure that the fluid level is several feet above the water table to ensure an excess headin the borehole. If the fluid level is not correct, an unexpected coarse zone can take a large volumeof fluid and the wall will collapse. Reverse cumulation is normally used for large diameter (over 30inches) holes, such as large irrigation wells. Permanent relief wells are often installed by reversecirculation because the well can be developed to a higher efficiency than with standard rotarydrilling. Theoretically, in reverse circulation, the maximum depth would not be limited. Themaximum depth without air assist is about 200 feet and with air assist is up to 400 feet.

b. Rig Configuration. Rig configuration for reverse cumulation rotary drilling (Figure 5-17)differs from rotary drilling. Hoisting and rotating the drill-string procedures are similar, but youmust change the fluid circulating system. All cuttings must pass through the drill string. Thesematerials could be granular, large grovel, and small cobbles. Occasionally, cobbles or smallboulders that are too large to pass can be wallowed to the bottom of the hole. When several largepieces accumulate in the hole, you will have to pull the drill string and remove the rocks, using anorange peel bucket or similar device.

Most reverse cumulation rigs are 6-inch ID and include items such as the drill string and hoses.The ports in the drill bit are smaller to prevent large particles from entering and becoming lodged.Pumps are available that can pass granular soil but not without damage. Pumps are not designedto handle large gravel. To prevent cuttings from passing through the pump, a jet eductor is used tocreate a vacuum. Water is pumped through the eductor at a high rate (600 to 1,200 GPM) producinga vacuum approaching 28 inches of mercury and pulling large volumes of water and cuttings. Boltedflanged pipe connections are popular. The flanged joint makes a reasonably smooth joint inside,

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FM 5-484/NAVFAC P-1065/AFMAN 32-1072

and the large torque required to rotate the bit does not over tighten the joint. Air bubbles injectedinto the circulation system at the bit increase turbulence and velocity and decrease fluid densityinside the drill string.

Reverse circulation drill pipe is fabricated from 6-inch ID tubing with standard pipe flangesand air pipes. Generally, two 3/4-inch pipes are welded 180 degrees apart along the outside of thedrill pipe with holes drilled through the flanges. These pipes are turned into the system near the bit.Compressed air is pumped through these pipes to assist in removing cuttings. The flanged pipeconnections are adaptable to the air-pipe alignment. The rotating swivel at the top of the drill stringis complicated by the need to inject air. Making connections to add a joint of flanged pipe is moretime consuming than with standard screwed-joint drill pipe. A 20-foot length is about maximumfor drill pipe. The vacuum lift is from the water level in the hole to the rotary water swivel; themaximum suction lift is 22 to 25 feet.

5-5. Drilling Information

a. Driller’s Log. Prepare a driller's log for every well drilled. The log contains data, such aswater-bearing-strata information, you use to locate and drill a well. Figure 5-18 (pages 5-35 and5-36) is an example of a well driller’s log (Department of Defense (DD) Form 2678). Figure 5-19(pages 5-37 and 5-38) is an example of a piping and casing log (DD Form 2679). These forms arein the back of this manual for reproduction and use. Items to record in the remarks section of thewell driller’s log could include the following:

Changes in circulation, color, and consistency of drilling fluid.Observations of the cuttings carried to the surface.Depth to material contacts.Size and apparent classification of the cuttings.Fluid loss or gain.Penetration rate.Soil description (fine or course, clay or sand).

b. Soil Sampling. Try to obtain good material samples, and log the depth from which thesamples came. Cuttings continuously wash to the surface during drilling. These cuttings are usefulbut are not the samples mentioned above. To collect a specific cutting sample, stop drilling andcontinue fluid circulation to wash most of the cuttings from the hole. When the hole is clean,advance the bit through the sampling interval and stop. Collect samples from the fluid of the drilledsection. Resume drilling after taking samples. Redundant sampling impacts on drilling progress.However, collect several samples regardless of schedule impact to obtain worthwhile information.Field modifications of well design are often required, especially when subsurface information hasbeen sparse. In most cases, the changes made during well drilling are minor. For example, placinga screen a few feet higher or lower to match the position of the most gravelly part of an aquifer, oradjusting a grout interval to match an impermeable layer above the aquifer.

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Chapter 6Well-Installation Procedures

6-1. Setting Casing. In rotary-drilled water wells, you can set the casing in the borehole after youfinish drilling. However, you must set the casing and grout it near the surface. This prevents theupper portion of the borehole from caving in.

For water wells drilled in rock aquifers, you can place the casing through the unconsolidatedstrata and into the rock to get a tight seal. However, this method does not ensure a tight seal. Youcan improve the seal by using the following procedures:

Step 1. Drill a borehole about 10 feet into the reck.Step 2. Flush the hole with clean water.Step 3. Fill the rock interval with grout, and immediately set the casing into the hole.

Let the grout set around the bottom of the casing.Step 4. Drill through the grout, plug in the lower casing, and progess into the aquifer.Step 5. Complete an open-hole well or install a smaller casing and screen inside the outer

casing.

NOTE: You cannot pour grout through drilling fluid to properly seal the casing.

6-2. Selecting Casing. Well casing is plastic, wrought iron, alloyed or unalloyed steel, or ingotiron. Well-completion kits have either plastic (Figure 6-1) or steel casing. You must know theproperties of other casings because you may have to use them. When selecting the casing, considerthe stress factor during the installation process, the corrosive element of the water, and the subsurfaceformation.

If you use casings other than thosein the well-completion kits, you mustspecify the weight per foot of pipe youwant to use. The tables in A100-66,American Water Works AssociationStandard for Deep Wells (AWWA),present data on the steel andwrought-iron pipes used as permanentwell casings. Joints for permanentcasings should have threadedcouplings or should be welded orcemented so they are watertight fromthe bottom of the casing to a pointabove ground. This precaution willprevent contaminated surface waterand groundwater from entering the

system. Table 6-1 (page 6-2) lists hole diameters for various sizes and types of well casings.

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6-3. Installing Casing.

a. Open-Hole Method. With this method, install casing using the following procedures:

Step 1. Clean the borehole by allowing the fluid to circulate with the drill bit close to thebottom so cuttings will come to the surface. You may carry the borehole deeper thannecessary so that if any material caves in, the material fills the extra space below thecasing depth.Step 2. Attach a coupling to the top of the casing. Suspend the casing by either attachinga hoisting plug to the coupling, using a sub (adapter) if necessary, or by placing a casingelevator or a pipe clamp around the casing under the coupling.Step 3. Lower the first length of casing until the coupling, casing elevator, or pipe clamprests either on the rotary table or on another support placed around the casing. If liftingwith a sub, unscrew the sub on the first length of casing and attach it to the second lengthof casing. If lifting by elevators or pipe clamps, release the elevator bails from the casingin the hole, and attach it to another elevator casing or pipe clamp on the second length ofcasing. Lift it into position, and screw it into the coupling of the first casing length.(Lightly coat the threads of the casing and coupling with a thin oil. Screw the lengthstightly together to prevent leaking.) Remove the elevator or other support from the casingin the hole and lower the string that is supported by the uppermost coupling.Step 4. Repeat the procedure for each casing length you install. If a cave-in occurs,attach a swivel to the casing with a sub, and circulate the drilling fluid through the casingto flush out the hole and wash the casing down. After the casing is set on the bottom ofthe hole, drill through the casing into the aquifer.

b. Single-String Method With this method, you install the casing and screen (that have beenjoined) in a single assembly. See paragraph 6-6a (page 6-10) for installation.

c. Wash-In Method (Jetted Wells). With this method, you advance the borehole for anexpedient jetted-well construction. See paragraph 9-2b(l) (page 9-3) for installation.

d. Driven Method (Driven Wells). Install the casing as with the borehole, the cable-tool, ordriven-point well method. See paragraph 9-3 (page 9-6) for installation.

e. Uncased-Interval Method. In rock, you normally leave the lower portion of the boreholeuncased because water emerges from irregular functions in the borehole wall. Therefore, for thewell to function properly, you must be careful when locating the bottom of the cased portion inrelation to any impermeable zone. Once you establish the depth, drill down and set the casing.Then drill a smaller hole to full depth and proceed with development.

6-4. Grouting and Sealing Casing. Once grout is mixed, it starts to set. Therefore, place themixture immediately after mixing it. You must have freshly mixed grout continuously to meetrequirements. Portland cement meets most grouting requirements. (You can use a quick-hardeningcement to save time.) For proper consistency, use no more than 6 gallons of water per 94-poundsack of cement. If you need a large amount of grout, add 1 cubic foot of fine or medium sand foreach sack of cement. Add a few pounds of bentonite or hydrated lime per sack of cement for abetter flow. For small jobs and if no equipment is available, use a 55-gallon steel drum as a mixingtank. Put 20 to 24 gallons of water in the bard and slowly add 4 bags of cement while stirring or

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jetting the water. Use as many mixing barrels as the job requires. If a concrete mixer is available,mix batches and dump them into a storage vat for future use.

You can force grout into place using pumps or air or water pressure. In some cases, you canplace grout using a dump bailer. If you use the tremie methods, you will need one or more stringsof pipe with small diameters. Other equipment you may need to place grout are a mixing tank,hoses, and a feed hopper.

a. Dump-Bailer Method. With this method, you can place grout simply and with a minimumamount of equipment. On the dump-bailer, the bottom valve opens and the operator can unloadgrout at a specified location. This method works best when you need to grout only the lower portionof the casing. Use the following procedures to place grout:

Step 1. Run the casing in the hole and mix enough grout to fill the lower 20 to 40 feetof the hole. (A quick method of mixing the grout is to put the required amount of waterin a barrel and circulate the water, using a high-pressure jet while adding cement.)Step 2. Place the grout inside the casing with a dump-bailer.Step 3. Lift the string of casing 20 to 40 feet off the bottom, depending on the amountof grout placed. The lower end of the casing should be below the top of the grout. Fillthe casing with water and cap the top.Step 4. Lower the casing to the bottom of the hole to force most of the grout up theannular space outside of the casing. Do not uncap the top of the casing until the grout isset.Step 5. Drill through the cement that has hardened in the lower end of the casing andcontinue drilling to the required depth. (Green cement will increase the viscosity of thedrilling mud.)

If you anticipate difficulty in filling the casing with water when it is lifted in the borehole, youcan add water on top of the grout without lifting the casing. Calculate the volume of grout in thecasing. Fill the casing to the top with water. Connect a pump so that you can force in additionalwater. Pump water into the casing, measuring the volume pumped, until you put in a quantity equalto the volume of grout. This will force all or most of the grout out of the lower end of the casing.You can place a wad of burlap on top of the grout before filling the casing with water to keep thefluids separated.

b. Inside-Tremie Method. With this method, you place the grout in the bottom of the holethrough a tremie pipe that is set inside the casing (Figure 6-2). The grout will either descendnaturally or you may have to pump it through the pipe. Make sure that the tremie pipe is at least 1inch in diameter. With this method and any other method where you place the grout inside thecasing, make sure that water or drilling fluid circulates up and around the casing before you startgrouting. To check this, cap the casing and pump in water. If the water comes to the surface outsidethe casing, you can start grouting. Use the following procedures to complete the tremie method:

Step 1. Continue pouring grout until it appears at the surface around the casing. Oncethe grout reaches the desired depth, it will fill the space around the outside of the casing.Step 2. Suspend the casing about 2 feet above the bottom of the borehole during theoperation. Once the grout is in place, lower and seat the casing in a permanent position.

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Remove and clean the tremie pipe. The check valve prevents the grout from movingback into the casing.Step 3. The grout should set and harden in about 24 to 72 hours, depending on the cementyou use. Drill out the packer and continue drilling the well below the grouted casing.

c. Outside-Tremie Method. With this method, you use a tremie pipe to deliver grouting outsidethe casing. This method is not recommended for depths greater than 100 feet. You can use thismethod if the space between the casing and the borehole wall is large enough to contain a 1-inchtremie pipe. Use the following procedures to complete grouting using this method

Step 1. Lower the pipe to the bottom. Make sure that the lower end of the casing istightly seated at the bottom of the borehole.Step 2. Mix a sufficient quantity of grout and pump it through the tremie pipe or let itdescend naturally (Figure 6-3, page 6-6). As the grout is placed, lift the tremie pipeslowly, but keep the lower end submerged in the grout.

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Step 3. Fill the casing with water as the grout is placed to balance the fluid pressureinside and outside the casing. Doing so prevents grout from leaking under the bottom ofthe casing.

You can quickly place grout near the surface using a tremie or by dumping the grout in the holearound the casing and puddling it with pipe lengths. However, this procedure only provides asurface seal around the casing and cannot be used as a normal grouting method.

6-5. Selecting Screens. The military uses continuous-slot screens (Figure 6-4) when drilling wellsusing the rotary method. You make the screens by winding triangular sections around a skeletonof longitudinal rods. Join the triangular sections and rods securely wherever they cress. The screensare constructed of either PVC or stainless steel and are packed in the well-completion kits. Someimportant factors to remember when selecting screens are that they--

Must produce a sand-free well of less than 2 ppm.Should prevent minimum head loss.Should be of a commercial grade. (Screen sizes are in increments of 0.005 inch.)Should lend themselves well to development (allow for a two-way flow).

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a. Types.

(1) PVC Screens. These screens must beat least 8inches in diameter. Continuous-slot PVC screens are inthe 600-foot well-completion kits packed in boxescontaining four 20-inch-long sections that can be joinedtogether (Figure 6-5). The kits should contain enoughsections to assemble up to 50 feet of continuous-slot, 8-inch well screen.

You can use the PVC casings to construct analternative screen. You saw or mill horizontal slots insections of the 20-foot-long casing. You cut six rows ofslots down the casing. The slots are 1/2 inch apart at awidth of 0.025 inch. You can construct PVC screens inthe field by cutting slots in PVC casing with saws.following lists saws and approximate slot sizes:

Hacksaw, about 0.035 inch.

Handsaw, 0.050 to 0.080 inch.

Circular saw, 0.100 to 0.125 inch.

These makeshift screens are not as efficientas the continuous-slot screens because of therelatively low open area per foot of screen.However, you should use these screens when thekit contains an insufficient number ofcontinuous-slot screens. The alternativescreens are the same as the casing sections. Youcan place the screens intermittently up the wellif you screen more than one aquifer or water-bearing strata. If you screen multiple intervals,you must place gravel packs around the screensand backfilling between the screens. Ifsufficient gravel-pack material is available, useit continuously to above the top of the screen.

(2) Stainless-Steel Screens. These screensare usually 6 inches in diameter and come in 10-and 20-foot sections. You can join the sectionsto make longer pieces. Most stocked screenshave 0.025-inch openings that are suitable for

The

medium-sand formations. Screens with other slot openings are available and may be needed forspecial installations. Various end fittings are available so you can use different installation methods.See paragraphs 6-6a through d (pages 6-10 through 6-12) for uses of these end fittings.

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(3) Pipe-Base screen. You make this screen by wrapping a trapezoidal-shaped wire around apipe base that has drilling holes evenly spaced. A pipe-base screen is strong and suitable for deepwells. The screen has two sets of openings. Outer openings are between adjacent turns of thewrapping wire and inner openings are the holes drilled in the pipe base. The percentage of openarea per foot of screen (usually low) governs the efficiency of the screen. These screens come in3- and 4-inch pipe bases for field operations.

b. Lengths. Use the electric logging units in the well-completion kits to determine the location,depth, and thickness of an aquifer. Screen length should not exceed the thickness of thin aquifers.You should screen the bottom third of unconfined aquifers and 75 to 80 percent of confined aquifers.However, for interlayered fine and coarse beds, consider the thickness of the coarse strata whendetermining screen length. Set the screen in the coarse strata. If you have a choice of slot sizes,consider the percentage of the open area or intake area of the well screen to determine length. Usethe following calculations to determine the amount of screen to use during drilling operations:

(1) Surface Area.

SA = π (OD) (12)

where-

SA = surface area, in inches per foot.OD = outside diameter of the screen, in inches.

(2) Open Area.

where-

OA = open area as a percentage.SO = slot opening, in inches.WD = wire diameter, in inches.

(3) Total Area.

TA = (SA)(OA)

where-

TA = total area, in square inches.SA = surface area, in inches per foot.OA = open area, as a percentage.

(4) Transmitting Capacity.

TC = (TA).31

where-

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TC = transmitting capacity, in GPM per foot of screen (based on one-tenth foot per minute ofvelocity).

TA = total area, in square inches.

(5) Screen Length.

where—

SL = screen length required, in linear feet.PR = pumping requirement, in GPM.TC = transmitting capacity, in GPM

The following example uses the above equations to determine the amount of 12-inch screenrequired at one-tenth foot per minute of velocity with a slot opening of 0.040 inch, a wire size of0.092 inch, and a pumping requirement of 800 GPM:

c. Diameters. The diameter of the well screen usually corresponds to the diameter of the wellcasing. If you are considering alternative diameters, consider the following:

Increasing the screen diameter to increase the yield or capacity of a well. The increaseis not proportional.

Doubling the diameter of a well screen increases the capacity of the well by about 10percent.

Using a larger diameter screen if the aquifer is thin or the pump is large.Using a long screen with a smaller diameter in a thick aquifer, for better performance.Increasing the length, not the diameter, of the screen to increase the yield of a well in athick aquifer.

d. Slot Sizes. You should understand the function of slot size in well construction. Whenpossible, choose the screen slot size to fit the gradation or grain sizes of the aquifer. Sand and gravelinteraction greatly affects the development of the formation around the screen. Small openings limitwell yield. Also, small slot sizes produce high velocity in the water passing through the screen. Intime, scale or incrustation tends to form on the screen. If the openings are too large, you may haveto develop the well more than usual, or you may not be able to clear the well of sand.

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Screen slots that are sized to retain the coarsest one-third to one-half of sand or gravel of theaquifer work best in a naturally developed well. About two-thirds of the sand in the layer behindthe screen should pass through the slots. A screen set across both coarse and fine strata may needsections with different slot sizes. If you have to pack the screen with gravel artificially, make surethe slot openings correspond to the size of the gravel you use. Screen openings that retain aboutnine tenths of the gravel work best.

6-6. Installing Screen. You can use several methods to install screens in rotary-drilled wells. Toset well screens, you will use the screen hook and casing elevators. You use the hook to engage abail in the bottom of the screen to suspend the screen on either the sand line or hoist line whilelowering the screen into the well (Figure 6-6). Do not pull the screen with the hook after theformation has closed in around the screen. If you are installing a screen using the telescoping methodand you must seal the casing, you will need rubber or neoprene packers. All screen-setting methodsrequire accurate and complete measurements of pipe, screen, cable length, and hole depth.

a. Single-String Method. With this method, youinstall the casing and screen as one assembly. Figure 6-7shows a single-string assembly equipped with fittings forthe washdown method. You can omit the washdownfittings if the hole stays open at the bottom. Use thefollowing procedures to install the assembly:

Step 1. Attach couplings to the top of the casingand screen section. Install a sand trap to thebottom of the string.Step 2. After running the entire string into theborehole, use casing elevators to carry most ofthe weight of the string until the formationcollapses in around the screen.Step 3. Run the drill pipe inside the casing tothe bottom of the screen, and pump water intothe well to displace the drilling fluid.Step 4. Raise and lower the drill pipe to washthe full length of the screen.

Step 5. Wait for the formation to settle aroundthe screen. Proceed with well completion anddevelopment.

For deep wells and wells requiring surface casing, you can use the following modifiedtelescoping procedure:

Step 1. Grout the surface casing in the borehole before you drill the well to the finaldepth.Step 2. Use the single-string method inside the surface casing, while bringing the innercasing to the surface.

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Step 3. After placing the gravel pack around the screen and impervious backfill on topof the grovel, grout the entire annulus between the inner and outer casing to the surface.

A disadvantage of the single-stringmethod is the weight of a long string of casingon top of the screen. When the screentouches bottom, it becomes a loaded columnthat can easily buckle because of itsslenderness. When the screen reaches thecorrect depth, you can prevent buckling bysupporting the screen on casing elevatorsuntil the formation material collapses aroundthe screen and supports it laterally.

b. Pull-Back Method. This is anothermethod of installing a telescoping screen.Use the following procedures for thismethod:

Step 1. Sink the well casing to thefull depth of the well, and clean outthe hole to the bottom of the pipewith the bailer.Step 2. Assemble the closed bailplug in the bottom of the screen.screw one or more packers to thetop of the bail plug.Step 3. Lower the screen insidethe well casing using the sand line.After setting the screen on thebottom, pull the casing back farenough to expose the screen in the aquifer and to a position where the packer is still insidethe casing.Step 4. Use a casing ring and slips with two hydraulic jacks to pull the pipe. If the screenmoves upward as you pull the pipe, lower the drill bit or other tool inside the screen tohold the screen down.Step 5. Hold the casing with pipe clamps until either the hole caves around the casingand grips the pipe or until you can place grout around the casing and the grout sets, afterpulling the casing to its permanent position.Step 6. Bail out the drilling mud so that the sand and gravel of the formation will closein around the screeen.

c. Open-Hole Method. Use this method to install telescoping screen when the depth andthickness of the aquifer have been predetermined. Use the following procedures for this method:

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Step 1. Sink the well casing into the aquifer to a depth slightly below the desired positionfrom the top of the well screen. Fix the casing in place by grouting or other means.Step 2. Mix drilling mud and fill the casing. Using a bit that will pass through the casing,drill into the aquifer below the casing to make room for the length of well screen to beexposed.Step 3. Lower the screen into position, ensuring that the rubber or neoprene packerremains inside the casing near its lower end when the screen is on bottom. If the hole istoo deep, drop gravel into the hole to the correct height.

Use the closed bail plug and the packer top-end fittings to support the screen and sand trap(Figure 6-8). With this method, the diameter of the screen must be smaller than the casing, sincethe hole drilled for the screen will be no larger than the inside diameter of the casing. Also, makesure that the packer fitting at the top of the screen is the proper size to seal inside the casing. Thedrilling mud must be heavy and thick to prevent the open borehole from caving in, and the mudmust be completely removed from the aquifer during development.

d. Washdown Method. This method works best if the aquifer is composed of fine to coarsesand with little or no gravel. The screen fittings you need for this method are a washdown or self-closing bottom. Figure 6-9 shows a fitting you can use when using a telescoping method to set thescreen through the casing. Set the casing from the surface to slightly below the depth where youwill install the top of the screen. Screw a section of wash pipe into the left-hand female thread ofthe self-closing bottom and attach the bottom to the screen or sand trap with the wash pipe projectingthrough the screen. Lift the entire assembly by the wash pipe and lower the screen inside the casing.Add sections of wash pipe until the bottom of the screen is near the lower end of the casing.

Use the following procedures for the washdown method:

Step 1. Connect the top of the wash pipe to the kelly and start the mud pump. Circulatewater (not drilling mud) down the wash pipe.Step 2. Let the screen move down as circulation continues and material washes. Takemeasurements and stop the descent of the screen when the packer is near the lower endof the casing. If drilling mud is still washing out of the well, continue pumping wateruntil most of the mud is displaced.Step 3. Stop the pump and let the aquifer close in around the screen. When the formationdevelops friction on the outer surface of the screen, turn the entire string of wash pipe tothe right to unscrew the left-hand joint at the bottom.Step 4. When the wash pipe is free, pump in more water. Raise and lower the stringseveral times so that the lower end travels the full length of the screen. This action willwash out more drilling mud and some fine sand from the formation.Step 5. Start development work. Remove the wash pipe and continue the developmentwork.

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e. Bail-Down Method. With this method, youneed special end fittings for the screen. Figure 6-10(page 6-14) shows an assembled bail-down shoe inthe bottom of the screen. The bail-down shoe has aspecial nipple that has right- and left-hand threadsand a coupling with right- and left-hand threads.Figure 6-11 (page 6-14) shows a shoe with a guidepipe that extends below the screen.

Use the following procedures for the bail-downoperation:

Step 1. Start the operation after you sinkthe well casing to its permanent position.The casing’s lower end should be slightlybelow where you install the top of thescreen.

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Step 2. Assemble the bail-downshoe, special nipple, and specialcoupling in the bottom of the screen.Step 3. Screw a length ofpremeasured pipe into the right-handhalf of the special coupling. Thispipe, which will extend up throughthe screen, is called the bailing pipeor conductor pipe.Step 4. Screw one or more packersto the top of the screen.Step 5. Lift the whole assembly bythe bailing pipe and lower the screeninside the well casing. Add lengthsof bailing pipe as the screen descendsuntil it reaches the bottom of theborehole.Step 6. Mark off the length of the screen on the bailing pipe that projects above thecasing, using the top of the casing as the reference measuring point. Run a bailer or sandpump inside the bailing pipe and start bailing sand from below the shoe.

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Step 7. As you remove sand from below the shoe by the bailer, the combined weight ofthe screen and the string of bailing pipe will cause the screen to move downward. Attachadditional weights to the bailing pipe, if necessary.Step 8. Monitor the progress of the work carefully, and stop the operation when thescreen reaches the desired depth. The packer should be near the lower end of the casing,but still inside the casing. Accurate measurements will avoid sinking the screen too far.Step 9. Drop a weighted and tapered wooden plug (Figure 6-11 ) through the bailing pipeto plug the special nipple on the bail-down shoe. When the plug is in place, unscrew theleft-hand threaded joint at the upper end of the nipple by turning the entire string of bailingpipe to the right. Remove the bailing pipe and proceed with well development.

If you use a different type of bail-down shoe, the left-hand threaded connection for the bailingpipe may be in the opening in the shoe or it may be in the packer fitting at the top of the screen. Ineither case, use the same procedures as above for operating the bailing down, plugging the bottom,and removing the bailing pipe.

Under certain conditions, you can bail down a well screen without using a bail-down shoe. Thebailing pipe is not connected to the screen. You fit the pipe’s lower end with a flange or couplinglarge enough to press on the packer at the top of the screen. The weight of the bailing pipe rests onthe screen. You fit the lower end of the screen with an open ring or a short piece of pipe. Be verycareful when using this method because the screen is not connected to the bailing pipe and youcannot control the screen’s movement from the surface. Careful measurements will prevent sinkingthe screen too far. This method should be limited to fairly short screens. Plug the bottom of thescreen by putting a small bag of dry concrete mix in the bottom and tapping the concrete lightlywith the drill bit or other tool.

6-7. Placing Gravel. The most important criteria for grovel pack (artificial sand filters) are cometgrain sizes and screen slot opening. Grading should be in proper relation to the grading of the sandin the aquifer. You could have trouble if you use gravel that is too coarse. Coarse, uniformly gradedfilter sand (about 1/8 inch) makes the best gravel pack for most fine-sand aquifers. You should usefine gravel (1/4-inch maximum size) to pack aquifers consisting of medium or coarse sand. Use ascreen with openings that cover about 90 percent of the gravel pack. The following is a field methodfor producing a filter material or gravel pack from a sand and gravel deposit for a medium sandaquifer.

Make two sieves with lumber. Cover one sieve with 1/4- to 3/8-inch hardware cloth.Cover the other sieve with window screen.

NOTE: A layer of hardware cloth under the screen provides extra strength to the sieve.

Discard all material that will not go through the hardware cloth but that will go throughthe window screen. Save the materials that the screen retains for analysis and loggingpurposes.

a. Open-Hole Placement. Where drilling mud keeps the borehole open, you can install a gravelpack using the positive-placement method. This method is the most common and best suited tomilitary field operations. Use the following procedures for this placement method:

Step 1. Drill a large diameter borehole the full depth of the well.

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Step 2. Set a smaller diameter screen and casing centered in the large diameter borehole.

NOTE: Basket-type centering guides work best.

Step 3. Fill the annular space around the screen with properly graded gravel.Step 4. Fill the borehole with gravel well above the top of the screen. Gravel worksdownward as sand and silt are removed from the formation around the gravel pack bysubsequent development.

Development work must be thorough when you drill the borehole using the rotary methodbecause the mud cake on the borehole wall is sandwiched between the gravel pack and the face ofthe formation. You must break up the mud cake and bring it up through the gravel into the well.Any mud cake not removed reduces the efficiency and yield of the completed well. To ensure thatyou remove all of the mud cake, limit the thickness of the gravel envelope around the screen to afew inches. A common mistake is to drill a very large borehole and use a small screen, making thegravel too thick for satisfactory results.

Another common mistake is to try and place gravel pack into a small annular space, such as 1inch. The gravel pack usually bridges at a coupling and does not get down around the well screen.A 2-inch annular space is minimum; 3-to 5-inch spaces are best. Remember, the annular space isthe difference between the outside of the casing and the wall of the borehole with the casing centeredin the hole. In most cases, you must also consider the outside diameter of the couplings.

b. Tremie Placement. You can use a tremie pipe when placing gravel-pack materials. Thefine and course particles should not separate, as in the open-hole placement, when the aggregatesettles through the drilling fluid in the well. Lower a string of 2-inch (or larger) pipe into the annularspace between the inner and outer casings. Feed the gravel into the hopper at the top of the pipe.Feed water into the pipe with the gravel to avoid bridging the material in the pipe. The pipe raisesas the gravel builds up around the well screen. The tremie system is practical for placing the gravelpack in shallow to moderately deep wells.

c. Bail-Down Placement. With this method, you can place a gravel pack as you install thescreen. Feed the grovel around the screen, it will go downward with the screen. The bail-downshoe used is somewhat larger than the screen so that gravel being added will follow down and aroundas the screen sinks in the formation. Figure 6-12 shows this operation. Development work is anessential part of this method. Screen openings must be larger than the grain size of the aquifer soenough aquifer sand will pass through and the gravel pack will replace the sand around the screen.

d. Double-Casing Placement. With this method, you place gravel and use a temporary outercasing (Figure 6-13, page 6-18). With this method, you pull back the casing as you pour gravel intothe space. This method is somewhat similar to pull-back screen installation.

6-8. Using Alternative Methods.

a. Formation Stabilizer. When you do not use a grovel pack you can place formation-stabilizermaterial to help prevent deterioration of the annular space outside the screen. Fine, loose strata maycave into that space, enter the screened interval, and degrade the well. The decision to use thismaterial usually occurs during the well-construction process. In unstable formations, considerstabilizing wherever the annular space is more than 2 inches thick.

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Grain size is important since you will develop the aquifer naturally, and as much as half of thestabilizing material could flow through the screen. The grain size should average slightly coarserthan that of the aquifer and should be well distributed. Widely used formation stabilize are

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Step 1. Center the screen at its final position in the open section of the borehole, usinga centralizer if needed.Step 2. Place the stabilizer material by dumping and tamping it down the hole or by usinga tremie. Raise the level of stabilizing material above the top of the screen and addadditional material as development progresses.Step 3. As you develop the well, the level of the stabilizing material drops as the materialis pulled into the screen. You must replace this material to maintain the level above thetop of the screen.

b. Unscreened Well. In competent rock, you usually tap the aquifer through numerous,irregularly spaced fractures. Once cleared of mud and rock fragments, the fracture stay open andthe intake interval functions efficiently for a longtime. You should not need a screen in such a rockwell. If you anticipate an unscreened-well design, you must be particularly attentive to the locationof the top of the unscreened intake interval and its relation to the position and thickness of anyimpermeable layer.

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Chapter 7Well-Completion Procedures

This Chapter implements STANAG 2885 ENGR.

7-1. Well Development. Table 7-1 shows the different well-development methods and somecharacteristics of each method. All methods are designed to produce a stable flow condition. Becareful not to let the drill strike the bottom plug during well development, especially when usingPVC pipe.

a. Jetting Method. With this method, you use a jetting tool that youlower inside the screen. Use the following procedures for this method:

Step 1. Attach the jetting tool (in the well-completion kit) to thebottom of the drill string (Figure 7-l).Step 2. Use the string to lower this tool into the screen.Step 3. Connect the upper end of the pipe to the kelly or thedischarge side of the mud pump.Step 4. Pump water into the screen and rotate the jetting toolslowly so that the horizontal jets of water wash out through thescreen openings.Step 5. Raise the string of pipe gradually and continue rotatingto backwash the entire surface of the screen. If possible, use apump pressure of 100 psi.

This backwashing method is effective in removing caked drilling mudfrom the borehole wall. A disadvantage in military field operations is thatthis method requires a large supply of water. After covering the entire screenwith the jetting tool, remove the tool. Remove the sand that has collectedin the sand trap with a bailer. Repeat this process until the well stopsproducing sand. If a significant volume of material is removed during

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development, you should add more filter material around the screen to keep the top of the grovelpack above the top of the screen.

b. Pump-Surge Method. This backwashing technique involves alternately pumping water tothe surface and letting the water run back into the well through the pump-column pipe. Use an air-lift pump or a deep-well turbine pump without a foot valve. See Chapter 4 for discussions on pumps.Do not use the permanent well pump for development. Pumping sand could damage the pump.Use the following procedure for this method:

Step 1. Start the pump. As water comes to the surface, stop the pump to release thewater. The power unit and starting equipment determine the starting and stopping actionof the pump. The effect is to lower and raise the water level in the well intermittentlythrough the screen openings. Periodically, pump the well to remove the sand brought inby surging.Step 2. Remove the pump and bail out the material in the sand trap, after surging.Step 3. Repeat the process until the well stops producing sand.

c. Gravity-Outflow Method. Backwashing by gravity outflow involves pouring water into thewell rapidly to produce outflow through the screen openings. Inflow through the screen is thenproduced by bailing water from the well rapidly. This is a slow surging technique requiring severalminutes to complete a cycle. If the static water level is high enough to permit pumping b y suctionlift, you can use a small centrifugal pump instead of the bailer to speed up the work. If there is roomin the well casing, connect the discharge side of the pump to a string of small diameter pipe that islowered into the well. The water added is pumped down inside the screen, creating a turbulencethat will help to develop the formation.

d. Pressure-Pumping Method. Occasionally, wells are backwashes by capping the casing andpumping water into the well under pressure. Water is forced outward through screen openingssimilar to the closed-well method of using compressed air for development (paragraph 7-1f(2), page7-5). Pressure pumping is an inefficient method because the desirable surging effect is difficult toproduce. You must make sure to seal the casing tightly in the borehole and prevent water frombeing forced up around the outside of the casing.

e. Surge-Block Method. With this method, water is surged up and down in the casing with asurge block or plunger. A surge block can be a solid plunger or swab or a plunger equipped withor without a valve opening (Figure 7-2). The valve-type plunger gives a lighter surging action thanthe solid type. Light surging is advantageous in developing tight formations. Therefore, start thesurging process slowly and increase the force as the development proceeds. Be careful whenworking with wells using PVC pipe. The casing or well screen could collapse from vigorous surgingaction. Plugging the valve of the plunger changes it to a solid-type plunger that you can use whenyou need greater surging force. Attach sufficient weight to the surge plunger to make it fall withthe same speed on the downstroke as the drilling machine uses on the upstroke. The drill stemprovides the weight required for the surge block. Use the following procedures for the surge-blockmethod:

Step 1. Lower the surge plunger into the well until it is in the water above the top of thescreen. Keep the plunger a few feet above the screen so that it will not strike the screenwhile surging.

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Step 2. Start surgingslowly and graduallyincrease the speed untilthe surge plunger rises andfalls without slack. Witha rotary rig, lift the plunger3 or 4 feet before droppingit. When using the sandline, control movement byusing the hoist brake andclutch.Step 3. Continue surgingfor several minutes. Pullthe plunger out of the welland lower the bailer orsand pump into the screen.When the bailer rests onthe sand that has beenpulled into the screen,check the depth of thesand by measuring on thesand line. Bail all the sandout of the screen.Step 4. Repeat the surgingoperation and compare thequantity of sand with thefirst quantity. Bailout thesand.

Step 5. Repeat surging and bailing until little or no sand can be pulled into the well.Lengthen the period of surging as the quantity of sand removed decreases.

f. Compressed-Air Methods. Compressed air provides rapid and effective development ofwells, using an open- or closed-well method. You can use the standard 350-cfm compressor fordeveloping most wells at a pressure of at least 100 psi. However, a higher pressure is preferable.The 250-cfm compressor will pump water by air lift from 100 to 150 GPM, depending on thesubmergence and size of the pipes you use. Table 7-2 (page 7-4) shows the recommended sizes ofpipe and air lines and the pumping rates you should use for various sizes of wells.

(1) Open-Well Method. The surging cycle is established by pumping from the well with anair lift and by dropping the air pipe suddenly to cut off the pumping. This cycle discharges largebubbles of compressed air into the screen. The submergence ratio must be 60 percent. Submergenceis the extent to which the air pipe is submerged in the water compared to the extent the pipe isbetween water and ground level. Work efficiency decreases rapidly as the submergence ratio dropsbelow 60 percent. In deep wells with a considerable head and a low submergence ratio, you canperform some effective work by shooting heads.

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Figure 7-3 shows the proper method of placing the drop pipe and airline in the well. Use ahoist line to easily handle the drop pipe. Suspend the air pipe on the sand line. Fit a T at the top ofthe drop pipe with a short discharge pipe at the side outlet. Wrap a sack around the air line whereit enters the drop pipe to keep water from spraying around the top of the well. Discharge from thecompressed air tank to the well should be the same size as or one size larger than the airline in thewell. Connect a quick-opening valve in the line near the tank. You need a pressure hose, 15 feetlong (minimum), for moving the drop pipe and air line up and down.

Use the following procedures to start developing the well using this method:

Step 1. Lower the drop pipe to within 2 feet of the bottom of the screen. Place the airline inside the drop pipe with its lower end 1 foot or more above the bottom of the dropline.Step 2. Let air enter into the airline and pump the well until the water appears to be freeof sand. Start slowly. If all the water is suddenly removed, the casing may collapse indeeper wells, especially when using PVC pipe.Step 3. Close the valve between the tank and airline and pump the tank full of air to apressure of 100 to 150 psi.Step 4. Lower the air line until it is about 1 foot below the drop pipe. Open thequick-opening valve so the air in the tank can rush with great force into the well. A brief,forceful head of water will emerge or shoot from the casing and from the drop pipe.Step 5. Pull the airline back into the drop pipe immediately after the first heavy load ofair shoots into the well. Doing so will cause a revered of flow in the drop pipe that willeffectively agitate the aquifer.Step 6. Let the well pump as an air lift for a short time and then shoot another head.Step 7. Repeat this process until no sand shows, indicating the completion of this stageof development.Step 8. Lift the drop pipe to a position 2 or 3 feet higher in the screen and follow thesame procedure. This develops the entire length of the screen a few feet at a time.Step 9. Return the drop pipe to its original position and shoot one or two more heads.Step 10. To complete the development process and thoroughly clean out any loose sand,pull the air line up into the drop pipe and use it as an air lift to pump the well.

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(2) Closed-Well Method. With this method, you use compressed air to close the top of thewell with a cap and arrange the equipment so air pressure can build up inside the casing to forcewater out through the screen openings (Figure 7-4, page 7-6).

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Disadvantages with this method are--

That valves and fittings may not be available for military field operations.The danger of forcing water upward outside of the casing. This will loosen the casingand could ruin the well by bringing clay down into the formation.

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Use the following procedures to develop a well using this method:

Step 1. Arrange the equipment as in Figure 7-4, and turn the three-way valve to deliverair down the air line, preferably with the air cock open. This will pump water out of thewell through the discharge pipe.Step 2. When clear water emerges, cut off the air and let the water in the well regain itsstatic level.Step 3. Listen to the air escaping through the air cock as the water rises in the casing todetermine stability. Close the air cock and turn the three-way valve to direct the air supplydown the bypass to the top of the well, forcing the water out of the casing and backthrough the screen. This technique will agitate the sand and break down any bridging ofthe sand grains. When the water has been pushed to the bottom of the drop pipe, airescapes through the drop line. You can prevent air logging of the formation by keepingthe drop pipe above the well screen.Step 4. Cut off the air supply and reopen the air cock so the water can reach the correctstatic level when you hear the air escaping from the discharge pipe or when the pressurestops increasing.Step 5. Turn the three-way valve and direct the air supply down the airline to pump thewell.Step 6. Repeat this process until the well is thoroughly developed. You should not haveto bail the well after developing it because the water velocity usually cleans out the sandfrom the well. However, if you did not initially bail the well thoroughly, you may haveto repeat the bailing process to clean out the well.

7-2. Dispersion Treatment. Dispersing agents, mainly polyphosphates, when added to drillingfluid, backwashing, jetting water, or water standing in the well, counteract the tendency of mud tostick to sand grains. These agents are procured locally on an as-need basis. Baroid Industriesproduces Barafos, a white, granular, sodium tetraphosphate thinner and dispersant.

You may use chemicals such as sodium hexametaphosphate, tetra sodium pyrophosphate,sodium tripolyphosphate, and sodium septaphosphate to develop wells. Dispersants workeffectively when applied at the rate of one-half pound of chemical to 100 gallons of water in thewell. Let the mixture stand for about one hour before starting well development. Wetting agents,such as CON DET, increase the dispersion action of polyphosphates when added to the solution ata ratio of 1:100. Be careful when using the dispersion process because you could have an adversereaction. The driller should make the decision to use or not to use dispersants.

7-3. Rock Development. Use this method to develop wells in rock formations. You can obtaingood results by combining jetting with air-lift pumping from a limited zone isolated by inflatablepackers. The objective is always to wash out fine cuttings, silt, and clay that have worked into thefissures, crevices, or pores of the rock during the drilling operations. Openings that remain pluggedreduce water flow into the well. Develop the well thoroughly to remove all obstructing material.When drilling through limestone formations, use acid to dissolve lime-like cementing material andto open up connections with joints or fissures beyond the borehole wall. However, such operationsare rare in military well drilling.

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7-4. Well Protection and Treatment

a. External Preparations. You should disinfect and protect a well before starting the borehole.Some other preventive measures are--

Stopping surface contaminants from entering the well.Ensuring that the drilling water’s quality is suitable.Cleaning and disinfecting all drilling equipment before starting a new well.Disinfecting the water used for drilling if you use a mud-based drilling fluid. If you usea synthetic drilling fluid, chlorinate the fluid. However, doing so will break down thefluid and reduce its life.Circumventing possible water-quality problems by stopping potentially harmful fittingsand equipment from entering the borehole. Carefully check the list of the hardware andmaterials placed and left in the well.

NOTE: Well casings should extend no more than 12 inches above the pump-house floor on a final-grade elevation and not less than 12 inches above the normal anticipated flood level.

b. Sealing Casing. A well must be carefully protected from sewage and other contaminantsthat could migrate down the well column to the aquifer and well screen. Sources of pollution couldbe on the surface or in shallow perched water, unusable aquifers, and intermittently saturated beds.Carefully planning the well’s location could help avoid the surface sources. However, you may notknow about subsurface contaminants until you start drilling the well. If that occurs, you will haveto alter plans and seal the well quickly. Chapter 6 discusses sealing or grouting operations. SeeSTANAG 2885 ENGR (Edition 2) for sealing a NATO well.

A rock well may be grouted from the lower end of the casing to the surface. You can placegrout between the inner and outer casings and around the inner casing in a portion of the drilledborehole below the outer casing. Make sure that overburden does not seal the borehole after youset the casing.

c. Disinfection. All newly constructed wells should be considered contaminated from theconstruction process and disinfected immediately after completion. Well-completion kits providepackages of a dry chlorinator for breaking down synthetic drilling fluids to disinfect the wells.Prepare a chlorine solution by--

Mixing 1 heaping tablespoon of calcium hypochlorite with water to make a thin paste.Break up all lumps.Stirring mixture into 1 quart of water. Let the mixture stand a short time.Pouring off the clear liquid.

The chlorine strength of the solution is about 1 percent. One quart of the liquid is enough todisinfect 1,000 gallons of water. Larger quantities of the solution may be prepared in the sameproportion and, if placed in sealed containers (preferably glass), can be stored for several yearswithout losing its effectiveness.

Estimate the volume of water standing in the well. Pour in the corresponding ratio of solutionto gallons of water in the well. (For safety, use less solution than too much solution.) Agitate the

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water in the well thoroughly and let it stand for several hours, preferably overnight. Flush the wellto remove all of the disinfecting agent. You can disinfect the well casing by returning water to thewell during the early stage of flushing and washing the walls with chlorinated water.

d. Cathodic Protection. A sacrificial anode (Figure 7-5) is the simplest method of protectingmetal casing from corrosion. Connect a galvanically active metal bar, such as magnesium-coatedwire, to the casing. Bury the anode bar near the casing below the water table. In this cell, ions flowto the casing through the groundwater. While the anode corrodes, the casing remains unaffected.Another method is to suspend cable (acting as the anode)into the well. The anode continues to operate and protectthe casing until it is consumed. (Periodically replace theanodes as continuing maintenance.)

e. Well Head and Collar. Use the well head in thewell-completion kit; otherwise, extend the casing at least1 foot above the general level of the surrounding surface.Seal the space around the outside of the casing by pouringa concrete platform around the casing at the surface(Figure 7-6, page 7-10). To form a concrete platform,you will need the following bill of materials (BOM):

Two 2-inch by 10-inch by 8-foot boards. Cutthese in half for the walls.Eight 2-foot long No. 4 reinforcement bars forthe comer stakes.One 4- by 4-foot wire mesh.About 0.5 cubic yard of concrete.

Use the following procedures to make the platform:

Step 1.

Step 2.Step 3.Step 4.Step 5.Step 6.Step 7.

Clear the site with shovels.

Dig a 4-inch excavation.Construct the form.Place the wire mesh, snipping out the center for the casing pipe.Mix and pour the concrete quickly.Pull the wire mesh up through the concrete.Screed with a 2-inch by 4-inch by 8-foot board.

If you do not have a container to mix the concrete, construct a mortar box using the followingmaterials:

One 4-foot by 8-foot by l/2-inch piece of plywood for the base.Four 2-inch by 6-inch by 8-foot boards for the walls.One 2-inch by 4-inch by 8-foot screed beam.

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NOTE: When mixing concrete, add the water slowly. Use 5 gallons of water per sack of concrete.Mix it with a hoe and place the concrete quickly.

The upper surface of this slab and its immediate surroundings should be gently sloping so waterwill drain away from the well. You should also place a drain around the outer edge of the slab andextend it to a discharge point that is far away from the well. A well with pipe casing should havea sanitary seal at the top that fills the space between the pump pipe and the well casing. This deviceconsists of a bushing or packing gland that makes a watertight connection.

7-5. Well-Completion Report. Figure 7-7 (pages 7-11 and 7-12) is an example of a military waterwell completion summary report (DD Form 2680). This form is used to update the world-wideresource data base. After you complete all well-drilling operations, fill out the form and send to theaddress on the form. DD Form 2680 is in the back of this manual for reproduction and use.

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Chapter 8Well-Performance Testing Procedures

8-1. Testing Pumps. You will normally use the permanent pump for pump testing. If you use atemporary unit, it must be adequate to draw down the water and hold it at a prescribed flow rate fora period of hours. This test will determine the specific capacity of the well. You can estimate theyield of a small well by bailing water from the well rapidly if no pump is available. You must knowthe bailer’s volume and count the number of times per minute the bailer is brought up full to estimatethe GPM of the well. Accurately measuring drawdown is not possible during the test because thewater level constantly fluctuates.

a. Permanent Wells. You should use two different testing procedures when a pump is available,depending on the intended use of the well and the available testing time. If the well will be apermanent installation and maintained in the future, you should conduct a detailed test. Measurethe static water level in the well before testing, and measure the drawdown during the test. Conductthe test as follows:

Pump at a rate that will lower the water in the well about one-third of the maximumdrawdown possible (one-third the distance from the static water level to the top of thewell screen) or about one-third of the rated capacity of the pump.Monitor and adjust the flow rate early in the test because as the drawdown increases theflow rate decreases.Continue pumping at a constant flow rate until the drawdown remains constant (about 1to 4 hours).Record the flow rate, drawdown, and testing time. Initially, take readings rapidly, andthen spread out the readings as the test continues. A reading schedule that doubles thetime between readings is preferable. The recommended schedule is as follows: 0 (at thestart of the test) 30 seconds, 1 minute, 2 minutes, 4 minutes, 8 minutes, 15 minutes, 30minutes, 1 hour, 2 hours, 4 hours, and so forth.Establish the desired, constant flow rate quickly. You must record the exact time of eachreading (not the intended or scheduled time). After the drawdown stabilizes (1 to 4hours), the pumping rate should increase to a new, constant flow rate, which will producetwo-thirds of the capacity of the pump. Do not stop the pump between these testsegments.Repeat the measurements, noting the exact time that the new flow rate was started. Tryto follow the above reading schedule, starting from the time the flow rate was increased.When the drawdown stabilizes, increase the pumping rate to produce the maximumdrawdown or about 90 percent of the maximum capacity of the pump. Conduct anotherreading schedule until the pumping level stabilizes.

You may modify the above procedure depending on well requirements and local site conditions.You should not modify the precision and accuracy of the measurements taken. Test results shouldbecome a part of the permanent records. The results are useful for evaluating the efficiency of thewell in the future and for determining the need for well rehabilitation. Calculating the GPM per

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foot of drawdown gives the capacity of the well. You can use this information to estimate productionand to regulate the pump’s flow rate to prevent dewatering of the well and possible pump damage.

b. Temporary Wells. Conduct a single-stage test rather than the step drawdown test. Toestablish the flow rate, conduct a 1- to 2-minute test to determine the GPM per foot of drawdown.Let the well return to the original static water level before testing (about 1 hour). Select a flow ratethat will produce about two-thirds of the available drawdown but will not reach more than 90 percentof the pump’s capacity. Conduct the test as described above, but with only one segment. Whenthe drawdown stabilizes for the selected flow rate, stop the test.

c. Methods. See Chapter 4 for a description of pumps used in testing and well production.

(1) Submersible-Pump Method. Use the submersible pump in well-completion kits to pumptest the water well. Set the pump deep enough to attain the maximum pumping rate and drawdown.When testing a well with a screen, set the suction of the pump above the top of the screen to preventlowering the water level below the screen. When testing a well without a screen, try not to dewaterthe production part of the aquifer. For proper testing, you must have a reliable power source so thattesting will not be interrupted. The power must be sufficient to drive the pump at a rated speed sothat full capacity can be developed.

(2) Air-Lift Method. This method is sometimes best for military field operations, especiallyif the well may produce sand that could damage or reduce the life of a submersible pump. An air-liftpump has two major problems. Air turbulence could make drawdown measuring difficult, andentrained air may cause considerable error in measuring the flow rate. After constructing an air-liftpump, check the pump capacity against the expected well yield. To conduct the test, set the pumpaccording to the readings in Table 4-2 (page 4-13).

An air compressor that puts out 350 cfm at 200 psi is suitable for performing most air-liftpumping operations. To determine the amount of air needed for pumping water, use the followingequation or refer to Figure 8-1.

where—

V = h = log = H = C =

free air (actual) required to raise one gallon of water, in cubic feet.total lift, in feet.logarithm-c value.operating submergence, in feet.constant (Table 8-1).

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The pressure required to start pumping will be equal to the depth of water over the submergedend of the air pipe. After pumping has started, the water in the well will draw down to a workinglevel. The air pressure required will be the total lift, in feet, from the working water level plus thefriction loss in the airline. Conduct the test and try to measure flow rate and drawdown quickly.Pumping creates turbulance in the well. Use the air-line method (paragraph 8-2c) to try and measuredrawdown. Because of entrained air, use the measured-container method (paragraph 8-3a) to obtainflow-rote measurements.

8-2. Measuring Water Level.

a. Electric-Line Method. Water levels can be measured accurately with a two-conductor,battery-powered indicator known as an M-Scope (Figure 8-2). Well-completion kits usually containan M-Scope. The M-Scope is a battery and a meter connected in series. When the upper wire onthe tip of the M-Scope in the well touches the water, the circuit is completed and the meter gives asteady reading. Measure the amount of wire in the well to determine the depth to the water level.The wire is marked at 5-foot intervals for easy measuring.

b. Tape Method. Use this method tomeasure the depth to the static level in ashallow well. Conduct this test as follows:

Chalk one end of a weighted steeltape with carpenter’s chalk. Lowerthe tape (Figure 8-3) into the wellto a depth of 1 or 2 feet past thechalk. (You can use soluble felt-tipmarkers as an alternative to chalk.)Measure the wetted length of thetape and subtract the amount fromthe total length lowered below thereference point to obtain the waterdepth. This test is accurate towithin 0.01 foot.

c. Air-Line Method. You can measurethe water level with an air line to followdrawdown and confirm a stable head during atest (Figure 8-4, page 8-6). The air line isusually 1/8- or l/4-inch copper tubing orgalvanized pipe that is long enough to extendbelow the lowest water level you aremeasuring. Fasten the air line to the pumpbowls or cylinder. Install the airline with thepump. The pipe must be airtight; makeup alljoints carefully. Measure the vertical lengthof the airline from the pressure gauge to thebottom of the line at the time of installation.

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Attach a pressure gauge to the airline at thesurface with an ordinary tire valve so you canpump air into the line. Pump air into the lineuntil you get a maximum reading. The readingshould be equal to the pressure exerted by thecolumn of water standing outside of the airline.Subtract the reading from the total verticallength of air line to get the depth to the waterbelow the center of the gauge. Readings aremeasured in feet, so you may have to convertyour figures.

8-3. Measuring Discharge Rate.

a. Measured-Container Method. You candetermine the flow rate from a well or pump bymeasuring the time required to fill a containerwith a known volume. With this method, usesmall containers for early measurements andlarge containers for later measurements. Also,use an instrument, such as a stop watch, foraccurate time measurements. Use the followingequation:

where—

FR = flow rate, in GPM.v = volume, in gallons.T = time required to fill container, in seconds.

b. Flow-Meter Method. A turbine-type flow meter will give an acceptable flow-rote reading.These meters are used by civilians. You can also use a totalizer-type water meter when the yield islow. Use these meters to measure the total gallons pumped and determine the flow rate. To do this,record the number of gallons that have flowed within a set amount of time and compute the flowrate.

c. Circular-Orifice Method. A circular-orifice meter (Figure 8-5, page 8-7) is a device youcan make to measure discharge rates. This device gives good results and is compact and easilyinstalled. The meter consists of a sharp-edged circular orifice at the end of a horizontal dischargepipe. The orifice is from one-half to three-fourths the diameter of the pipe. The inside of the pipemust be smooth and free from obstructions for a length of 6 feet from the orifice. The dischargepipe has a small hole on one side with a rubber-tube connection. The pipe is designed so that youcan measure the pressure (head) in the discharge pipe at a distance of 2 feet from the orifice.

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The length of hose and ruler depends on the pipe size you use (Table 8-2). The discharge pipemust be horizontal, and the stream must fall free from the orifice. The orifice must be vertical andcentered in the discharge pipe. The combination of pipe and orifice diameters for a given test shouldbe such that the head measured will be at least three times the diameter of the orifice.

d. Open-Pipe Method. With this method, the pipe is fully open and you measure the distancethe water stream travels parallel to the pipe at a 12-inch vertical drop (Figure 8-6, page 8-8). Usethe following procedure:

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Step 1. Measure theinside diameter of the pipeand the distance thestream travels parallel tothe pipe at a 12-inchvertical drop. Yourresults will be in inches.Step 2. Estimate the flowfrom the pipe diameterand the distance thestream travels (Table 8-3,page 8-8). Your resultswill be in GPM.

For partially filled pipes,measure either the water depth or thefreeboard. Divide the diameter bythe water depth to get a percentageratio. Measure the stream as aboveand calculate the discharge. Theactual discharge will be,approximately, the value for a fullpipe of the same diameter multipliedby the correction factor from Table8-4 (page 8-8).

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Part Three. Special Considerations

Chapter 9Alternative Well Construction

9-1. Fundamentals. Under special conditions, methods other than the rotary and down-holehammer may be more expedient for well drilling. Conditions favoring less standard methods includethe following:

Availability of local, nonstandard drilling equipment and qualified personnel.A shallow aquifer that can be developed quickly without mobilization delays.Availability of unskilled personnel only.Requirements for a small water supply.

9-2. Jetted Wells. In the jetting method, you dig a borehole using a high velocity stream of water.The stream loosens the soil and washes the fine particles up and out of the borehole. The jettingmethod is particularly successful in sandy soils when the water table is close to the surface. Jettingis simple and dependable, and you use hand tools rather than bulky drilling equipment. Two jettingprocedures are available washing in a casing or sinking a self-jetting well point. With the jettingmethod, you can sample the general character of a formation by examining the cuttings brought tothe surface in the return flow.

a. Equipment.

(1) Swivel. The water swivel must be able tocarry the weight of the drill pipe and must sustainthe maximum pressure delivered by the pump.Figure 9-1 shows a connection that you may use atthe top of small-diameter jetting pipes in place of aswivel.

(2) Drive Weight. This is weight you drop onthe pipe to help penetrate clayey or semifirm soil.

(3) Jetting Fluid. Water is commonly used injetting, but a fluid with greater viscosity and weightmay be prepared with clay or commercial bentonite.However, a heavier fluid tends to seal the boreholewall, preventing water penetration. In the jettingprocess, fluid is led from the borehole to a pit wherecuttings settle to the bottom. The jetting pump thenrecirculates this fluid. Under certain conditions inthe Arctic, steam is used to construct jetted wells.

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(4) Hoist. You need a hoist to handle the drill pipe and casing. You may use hand-operatedequipment such as a tripod with tackle. If available, you should use a percussion-type drilling rigwith a power hoist (Figure 9-2).

(5) Pump. A pump with suitable hose connection able to deliver 50 to 100 GPM at 50 psi isadequate. The quantity of water needed to jet a well varies with the type of sediment beingpenetrated. Sand requires the most water; however, high pressure is not necessary. A nozzlepressure of 40 psi is usually sufficient. Clay and hardpan require less water. However, they are not

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readily displaced except by a small cutting stream delivered at high pressure. You can get a pressureof 200 psi from small nozzles in the drill bit.

(6) Bits. In soft soil, you may use a paddy or expansion bit to make a hole that is slightly largerthan the casing. Use the percussion method with a hand rig and straight bits to penetrate hard layers.Use drill-like bits with heavier rigs to penetrate hard layers that do not yield to the water jet. SeeFigure 9-3 for bits used in jetting.

b. Methods.

(1) Wash-In. Before washing the casing into the hole, cut the lower end of the casing to forma toothed cutting head (Figure 9-4, page 9-4). Normally, four to six l-inch long (minimum) teethare sufficient. Use the following steps to complete the wash-in method:

Step 1. Mark the outlines of the teeth on the casing using a power drill or cutting torch.Drill or cut holes in the casing to form the gullets of the teeth.

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Step 2. Cut the sides of the teeth with a hacksawor an oxyacetylene torch to meet the outsidecircumference of the drilled holes. Roundedholes are desirable so the teeth can readily clearthemselves of gravel or other material. Bend halfthe teeth outward so they cut a hole slightly largerthan the casing.Step 3. Place a capon the top of the casing, andattach the discharge hose from the pump to theconnection provided in the top of the cap.Suspend the casing vertically, using a hoist. Laythe cutting head on the ground, preferably in ashallow, hand-dug hole. The majority of thecasing’s weight should rest on the ground.Step 4. Operate the jetting pump at full capacity.The casing will fill with water and begin to sinkby its own weight as the ground is washed outfrom under it. The hoist must keep sufficienttension on the casing to hold it vertical. Ifresistance stops the downward movement of thecasing, lift it up 2 or 3 feet and then drop thecasing.Step 5. Use chain tongs or wrenches to rotate thecasing so the teeth at the lower end will cut intothe bottom of the borehole. If you wash in morethan one length of casing, keep the borehole andfirst length of casing full of water while attachingthe second pipe length and connecting the pumpto the pipe. Doing so maintains fluid pressureagainst the borehole wall and should prevent caving.Step 6. Stop the pump, and remove the cap at the top of the casing when the casingreaches the desired depth.

If the casing is permanent, telescope a well semen through the casing until it rests on the bottomof the well. Pull the casing up until the screen is exposed to the aquifer and cut the casing off at apoint about 1 foot above the ground surface. If the casing is temporary, attach a well pipe to thescreen before lowering it into the casing. When the screen is resting on the bottom of the borehole,pull the entire casing out of the borehole. You can reuse this casing.

(2) Self-Jetting. Figure 9-5 shows the well-point types needed in self-jetting. The continuousslot has a semen constructed of a narrow ribbon of metal wound spirally around a skeleton oflongitudinal rods. The brass jacket consists of a woven wire gauze wrapped around a perforatedpipe and covered with perforated brass sheet. The jetting head contains a spring-loaded disk or ball-type valve that opens when water is forced through during the jetting operation. The valve closesautomatically when jetting stops or the well is completed and pumping begins.

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Use the following steps for the self-jetting method:

Step 1. Couple the well point to the bottom of the riser or well pipe. Attach the swivelto the other end of the well pipe. Connect the discharge hose of the pump to the swivel,and dig a shallow hole.Step 2. Upend the well-point assembly with the well point standing vertically in the hole.Start the pump and partially open the discharge valve. The jet of water will displace theself-closing valve in the well point and flow through the openings in the head. The soilis washed from under the well point, allowing the point to sink into the ground. Usingan up-and down movement of the well-point assembly will speed penetration.Step 3. Increase the water flow by opening the pump discharge valve more as jettingcontinues. Inmost sands, a pressure of 40 psi at the well-point nozzle will displace soilreadily. You may need pressures of 100 to 150 psi to move gravel or penetrate clay. Ifa regular jetting pump is not available, two standard centrifugal pumps operating in seriesmay work satisfactorily.Step 4. Remove the hose from the riser pipe, and couple the pipe to the suction side ofthe pump after sinking the well point to the desired depth.Step 5. Develop the well by quickly opening and closing the discharge valve whileoperating the pump at a moderate speed. Continue this operation until you clean out allof the fine material from the well-point screen.

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(3) Casing and Completion. Jetting fluid effectively prevents caving or collapse of the drilledhole. Insert the casing in a single string only after jetting reaches the full depth. If you do so before,the casing sinks as fast as jetting proceeds. If you encounter too much resistance, you may have toforce the casing down. For depths of 200 to 300 feet, you can use a casing of 4-inch diameter pipe.If you sink a deeper well, place a smaller string (3-inch diameter pipe) inside the first string.

To complete the jetted well, connect a hose to the exposed end of the well pipe and couple itto the pump intake. The well will yield water immediately if the pump is in good condition andyou have properly placed the well screen. When you first start pumping, a considerable amount offine sand will be drawn into the well screen and be discharged with the water. Because of thisaction, direct the water stream into the annular space around the well pipe at the ground level. Doingso washes the coarse sand and gravel into the borehole and packs the sand and gravel firmly aroundthe well screen and pipe. The well is then ready for continuous pumping.

9-3. Driven-Point Wells. Small-diameter driven wells are constructed by driving a drive pointfitted to the lower end of tightly connected pipe sections into the ground (Figure 9-6). The drivepoint consists of a perforated pipe with a steel point at its lower end to break through pebbles orthin hard layers. Use 5- to 6-foot pipe sections for the pipe string and as the casing for the completedwell. Driven wells are usually 1 1/4 to 2 inches in diameter. The small diameter pipe required forthese wells is light and portable and is easy to install. You can also construct wells up to 4 inchesin diameter. The casing used in these wells is heavier and more difficult to drive. However, youcan install deep-well pumps in the pipe casing to a depth of 25 feet or more below ground. If youuse a common pitcher or a centrifugal pump, the water level should not be deeper than 25 feet.

a. Equipment.

(1) Drive Points. The continuous-slot drive point (Figure 9-7, page 9-8) has a screen withhorizontal openings and one-piece welded construction and contains no internal perforated pipe torestrict the intake area. The pipe will withstand hard driving but should not be twisted while beingdriven.

The brass-jacket type consists of a perforated pipe wrapped with wire mesh and covered witha perforated brass sheet. Because the pipe body must be strong, the number and size of holes arelimited, restricting the effective intake area.

The brass-tube type consists of a brass tube slipped over perforated steel pipe for a ruggedconstruction. This tube has about the same intake area as the brass-jacket type. All drive pointshave steel-point bottoms and pipe-shank tops. The brass-jacket types have steel points with awidened shoulder to push gravel or rocks aside and reduce the danger of ripping or puncturing thejacket.

(2) Drive Pipe. Standard drive pipe is furnished in 6- and 8-inch sizes, with the dimensionsas shown in Table 9-1 (page 9-8). The two ends of the pipe should meet in the center of the coupling,making a butt joint (Figure 9-8, page 9-9). Drive pipe threads are not interchangeable with standardpipe threads.

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(3) Drive Clamps. Drive clamps (Figure 9-9) used in drivingcasing or pipe are attached to the square of the drill stem. Whendriving the clamps, strike the drive head or coupling at the top of thecasing. The stem acts as a guide through the head and furnishes theweight needed for driving.

(4) Drive Heads. Drive heads (Figure 9-10) placed on the pipeprotect the threads from the driving blows of the drive clamps. Thedrive heads are put on by unscrewing the bit, slipping the drive headover the drilling stem, and making up the joint again. If you use thescrew drive head, make sure you unscrew the drive head from thepipe coupling before pulling the tools from the hole.

(5) Drive Shoe. Always attach a drive shoe(Figure 9-11) to the lower end of the pipe to preventthe pipe from crumpling while being driven. Adrive shoe is threaded to fit the pipe or casing. Theinside diameter of the shoe below the shoulder isthe same as the inside diameter of the pipe. A driveshoe is forged of high-carbon steel, without welds,and is hardened at the cutting edge to withstandhard driving. Screw the drive shoe tightly to buttthe inside shoulder against the end of the pipe.

(6) Elevator, Sand Line, and Pin Hook (Figure9-12, page 9-10). Use casing elevators to handlepipe. The device clamps around the pipe directlyunder the coupling. You can use the sand line withthe elevator for lifting one or two half lengths ofpipe. For heavier strings of pipe, use the elevatorwith the swivel hook attached to the rope socket onthe drilling line.

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(7) Casing Ring andSlips (Figure 9-12). Usea casing ring to suspendthe casing at the groundsurface and for pullingpipe from the hole usingjacks placed under eachside of the casing ring.The rings are made of caststeel and are fitted withhandles. All slips are caststeel, with sharp teethproperly hardened.

(8) Pipe Tongs(Figure 9-12). Use chaintongs to tighten the 6- and8-inch drive pipe.Should the pipe turn inthe hole while adding atop length, hold the lowerpipe with one tong andtighten the top lengthwith another. If frictionin the borehole is enoughto hold the pipe while

making up top lengths, use both tongs on the top length, opposite each other. Doing so puts an evenstrain on the pipe, eases the operation, and makes abetter joint. Pipe joints must be tight and kepttight while driving pipe; however, keep tong pressure low enough to avoid collapse of the pipe.

(9) Pipe Clamps (Figure 9-13). You canconstruct wooden pipe clamps for 6- and 8-inchdrive pipe. You can use the clamps to hold the pipeat any position in the hole during drillingoperations.

b. Procedures.

(1) Borehole. Generally, driven wells arestarted in a hole bored with a hand auger. Thediameter of the borehole should be larger than thatof the well point, and the borehole should be asdeep as the auger will work. In clay soils, boringwith an auger is much faster than drilling.

(2) Pipe Joints. Construct pipe jointscarefully so that joints are airtight to preventthreads from breaking. If available, use special

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drive-pipe couplings (Figure 9-14). Screw all joints tightly after cleaning and oiling the threads. Usejoint compound to improve airtightness. When transporting and storing joints, you should protectthem with caps or couplings. To ensure that joints remain tight, give the pipe a fraction of a turnwith a wrench after each blow until the upper pipe joint sets permanently. Do not twist the pipestring while driving.

(3) Pipe. You must keep the well pipe vertical. To check the angle, hold a plumb bob at arm’slength from the well pipe and from two directions at right angles to each other. If the pipe is notvertical during the early part of the driving, straighten it by pushing on the pipe while the blows aredelivered. If you cannot straighten the pipe, withdrew it and start in a new location.

Use a maul or sledge to strike the drive capon the well pipe. Hit the drive cap squarely to avoidpipe damage. An alternative to manual driving is a driver that fits over the drive cap. If available,use a pneumatic tamper or sheet pile driver with an air compressor if the pipe is strong. A weakpipe will break at the couplings if you do not use a butt joint.

(4) Casing. If you use unthreaded casing, butt-weld the casing lengths. Use an alignmentcollar for initial tack welding (Figure 9-15, page 9- 12). The collar is used to align the pipe or casingto get a straight, tight joint. With the welded casing, you can drive a pipe string and possiblyeliminate casing damage. Remove the collars when you complete tack welding.

Another driving method involves a steel driving bar attached to a rope. The bar falls freelyinside the pipe and strikes the base of the drive point (Figure 9-16, page 9-13). This method is safestbecause it does not weaken the pipe.

The falling-weight method uses a drive monkey, which is a weight that slides over the pipe(Figure 9-17, page 9-14). A simple arrangement of this method is one in which the monkey slideson a bar supported by the well pipe. Use a drive cap with this arrangement. Another method is toslide the drive monkey over the well pipe to strike the drive clamp that is around the well pipe. Youmust use a tripod with either method. In soft formations, the descent rate may be 2 or 3 inches perblow. In sand or compact clay, using water in and around the pipe makes driving easier. Extremelycompact clay is difficult to penetrate and requires many blows to penetrate a few inches.

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Successful construction of driven wells depends on close observation and correct interpretationof certain work aspects while driving. Interpretation of details such as penetration made with eachblow, drop and rebound of the maul or weight, sound of the blow, and resistance of the pipe torotation helps the well driver to determine the character of the materials being penetrated. Table9-2 (page 9-15) outlines a guide for the identification of the formation being penetrated.

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c. Well Completion.

(1) Straight-Pumping Method. You can develop a well with a pitcher-spout hand pump. Thepump has a plunger and a check valve arranged so that the check valve trips when you raise thepump handle as high as possible. With this method, you can pump for an extended period beforetripping the check valve. Tripping allows water to run back down the well pipe. By applying aheavy suction on the well and tripping the valve, you produce a surging action through the screenopenings. The flow reversal, due to the surging, loosens the fine material plugging the screenopenings and brings the fine sand and silt into the well point. If you pump continuously for severe1minutes, these particles may be raised from the well. When the flow is clear, the well is ready foruse. Check the pump to ensure that the valves and plunger are free of sand.

(2) Alternative Completion Methods. If you cannot clear all the sediment from the well pointby pumping, try any of the following methods:

Method 1. Lower a series of connected lengths of 3/4-inch pipe into the well with thelower end resting on the sediment in the well point. Clamp the pipe in position and attacha hand pump to the upper end. Run water into the well pipe (not the 3/4-inch pipe) andoperate the hand pumps. By steadily pumping, the sediment will be lifted through the3/4-inch pipe. Continue to lower the 3/4-inch pipe to the sediment level until the well iscleared.

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Method 2. Insert a string of 3/4-inch pipe into the well and fill the well with water.Repeatedly raise and lower the pipe sharply. Hold your thumb over the top of the 3/4-inchpipe during upward movements, and remove your thumb during downward movements.A jet of muddy water is expelled on each downward stroke. When the material loosensand is suspended, you can pump out the muddy water.Method 3. Pump water into a string of 3/4-inch pipe that is resting on the sediment toremove the fine material by a jetting action. This procedure requires a large supply ofwater and a motor-driven or hand-force pump.

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9-4. Cable-Tool Method.a. General. Cable-tool drilling (churn drilling) produces a chopping action. The method and

the tool are not expensive, and one person can operate the rig. Cable-tool drilling is a very slowmethod and is not as widely used as rotary drilling and percussion drilling are used. You can usea cable-tool drill to penetrate rocky soil or moderately hard sedimentary rock. The drill does notrequire large amounts of drilling fluid. Since the borehole is not full of fluid, you must drive casingas you dig the hole deeper to stabilize the wall.

b. Equipment and Procedure.

(1) Rig. The rig consists of a winch with a large wire-rope reel, a walking beam, and a mast.Make sure the wire rope is long enough to reach the anticipated depth. Advance the borehole usinga suspended bit for chopping the soil or rock at the bottom of the hole. Thread the wire rope throughthe walking beam and over a sleeve at the top of the mast. As the walking beam goes down, the bitis lifted; as the walking beam comes up, the bit is dropped. As you dig the borehole, unreel the ropeto keep the bit just at the bottom. If the borehole is dry, add water to a few feet off the bottom. Asyou lift and drop the drill bit, the material is chopped and mixed with the water. After an advanceof a few feet, use a bailer to remove the mud.

(2) Tools. A complete set of drilling tools includes the chopping bit and a set of heavy drilljars located above the bit. The stroke of the drill jars is such that when the walking beam is all theway down, the bit is above the bottom of the hole. When the walking beam goes up, the bit dropsto the bottom of the hole; as the drill jars close, the bit is impacted. Using a drive barrel and longjars, take a sample from the bottom. The stroke of the long jars is longer than the stroke of thewalking beam so that the drive barrel is not lifted off the bottom of the hole while driving with theimpact of the jars. Cable-tool drilling involves many cycles. Each cycle involves reeling andunreeling wire rope and is a slower operation compared to a cycle on a rotary rig.

9-5. Augered Wells. You can construct bored wells using hand- or power-driven earth augers.Boring is practical where groundwater can be obtained at shallow depths and when small quantitiesare needed. Augered boreholes range from 2 to 32 inches in diameter and reach depths of 25 to 50feet. Engineer troops can construct small-diameter bored wells using organizational equipment.

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a. Equipment.

(1) Hand Auger. These augers consist of a shaft or pipe with a wooden handle at the top anda bit with curved blades at the bottom. The standard engineer auger has fixed blades, but there arebits with blades adaptable to different diameters. Hand augers usually come with several shaftextensions and couplings. To add an extension, remove the handle, couple a section to the pipe,and replace the handle. Hand augers can penetrate clay, silt, and those sands in which an openborehole will stand without caving.

(2) Power Auger. These augers are rotated, raised, and lowered by power-driven mechanisms.The turning force is transmitted to the auger through jointed square or polygonal stems. The powerauger issued to engineer troops has a depth limit of about 10 feet. You can use this auger only inareas where the water table is close to the surface.

b. Procedures. To start boring with an auger, force the auger blades into the soil while turningthe tool. The auger will cut into the ground at a rate determined by the hardness of the soil. Whenthe space between the blades is full of material, remove the auger and empty it. Repeat the operationuntil you reach the desired depth.

When constructing bored wells, you may hit small rocks or boulders that will prevent furtherpenetration. When this occurs, lift the auger from the hole; remove the cutting bit, and replace itwith a spiral or ram’s horn. Lower the tool into the hole and turn the auger clockwise. The spinalshould twist around the rock so you can lift the rock to the surface. Remove the spiral, replace itwith the regular bit, and continue boring. If you hit a large boulder that you cannot remove with aspiral, abandon the hole and start somewhere else. Wells less than 15 feet deep should not requireequipment other than the auger. For deeper wells, use a light tripod with a pulley at the top or araised platform so you can insert and remove a longer auger rod from the hole without damagingthe rod and without unscrewing all pipe sections.

c. Well Completion. If you reach loose sand and gravel, you may not be able to bore belowthe water table. To overcome this problem, lower a pipe or other casing to the bottom of the holeand continue to remove material while adding weight at the top of the casing to force the pipe down.If you cannot remove material from the hole, use a bailer or sand pump and make the hole deeper.Complete bored wells by installing well screens in the aquifer and developing the well as describedin Chapter 7. You may also use drive points (paragraph 9-3a(l), page 9-6).

If you find groundwater in jointed clay, complete bored wells by lining the hole with clay tile.Use bell- and spigot-type tile and set the tile in the hole with the bell ends down. Pour coarse sandaround the tile. You cannot ensure a sanitary well using this completion method. Therefore, usethis method when it is the only possible solution.

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Chapter 10Arctic Well Construction

10-1. Considerations.

a. Arctic Water Supply. Supplying water for operations or bases in the Arctic and adjacentcold regions requires careful planning due to the harsh climate and ground conditions. Potable wateris widespread at the surface in some cold regions but is uncommon in more arid cold regions.Locally, surface water can be melted from ice or pumped from unfrozen lakes or glacial-melt pools.Many surface sources are only dependable during the summer months, leaving potential problemsin supplying water throughout the year. More dependable, year-round supplies of groundwater maybe developed through wells in relatively shallow, unfrozen strata (Figure 10-1) and from wells thatfully penetrate the permafrost.

WARNINGDo not touch cold metalwith your bare hands.

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Permanently frozen rock and soil are widespread in the Arctic north of 50oN latitude. Thiscondition restricts groundwater development because some of the groundwater is permanentlyfrozen and not available. The frozen zones, which vary in thickness from a few feet to 2,000 feet,are impermeable aquicludes and inhibit the upward movement of unfrozen groundwater. Thedifficulty of obtaining water increases northward as the permafrost thickens and becomes colderand more continuous.

b. Discontinuous Permafrost. In this zone, permafrost will be thin and may be absent on thesouth slopes of hills, in valley bottoms containing permeable alluvial material (sand and grovel),and under surfaces that have been cleared of vegetation (airport runways, farmlands, forest-firescars, and logging tracts). Obtain information from local sources regarding springs (icings), existingwells, unfrozen zones, and caves used for storage. Consider obtaining water from surface sourcesbefore drilling and developing wells in the permafrost zone. The existence of a good, year-roundwater source at the surface in the discontinuous zone will indicate that the ground is not frozenbeneath the well. Year-round springs, large streams, and lakes can serve as water sources. Even ifthe water is unpotable, these sources indicate windows in the permafrost where dug, driven, jetted,or drilled wells may be located.

Vegetation could indicate the presence and thickness of permafrost. Tree roots rarely exceeda depth of 3 feet. Therefore, the presence of large trees may indicate that only the top of thepermafrost during the thawing season is deeper than usual. Large trees along a river could suggestthat either the top of the permafrost is depressed to afford a limited supply of water or that permafrostmay be absent. The presence of pine or aspen may indicate a similar depression of the permafrosttable or possibly the complete absence of permafrost. The presence of willow shrubs (not trees),peat and moss, or stunted tamarack and birches may indicate a thin zone of summer thawing (activezone) and the presence of cold, thick permafrost near the surface. These indicators are more frequentin a thick, continuous permafrost zone.

c. Thick, Continuous Permafrost. Generally, you will have to use surface sources whenunderlain by thick, continuous permafrost. Available groundwater will require drilling deep(several hundred feet) wells through the permafrost. Such a task may be beyond the scope of amilitary operation.

10-2. Well Drilling.

a. Drilling Equipment. You will use the same drilling equipment as for normal well drillingand additional accessories required because of adverse weather conditions. You will need portablegasoline or diesel heaters for personnel and equipment at the construction site. You will also needelectrical or oil immersion heaters for storage and settling reservoirs. You should have tents orsheds as protection for personnel from cold winds or storms.

b. Rotary Drilling. In permafrost regions, use the rotary-drilling method for deep drilling andlarge diameter holes and for shallow drilling and small holes. The procedure for rotary drilling infrigid climates is the same as in temperate climates except for temperature requirements of thedrilling fluid. In adverse weather conditions (extremely low temperatures and snowstorms),construct shelters to protect the rigs and to maintain comfortable working temperatures.

At temperatures below -20°F, generally no drilling is done. The mud used in rotary drillingshould beat near-freezing temperatures when entering the drill stem to prevent thawing and caving

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of the hole. When necessary, apply enough heat to the mud to prevent the hole from freezing. Makesure the rig operates continuously to prevent the mud pump and accessories, bits, and casing fromfreezing during operations. If you must stop operations at night, remove the tools, let ice form, anddrill out the ice in the morning. In a finished well, you can use the rotary rig to circulate the waterto prevent freezing until you can install a pump.

c. Jet-Drive Drilling. This is another method of constructing small wells in cold climates. Youcan also use this method in warm or discontinuous permafrost. The wells are usually 2 inches indiameter and are drilled to a depth of 200 feet. Use the procedures and equipment described inChapter 9 to construct the wells.

The equipment is simple and light and consists of small derrick and a small engine with acathead. You push the pipe into the ground and advance it manually dropping a small weightfastened to a line running over a sheave on the derrick to the cathead. The jet point is made froma reducer, which is ground into a bullet shape and attached to the end of the 2-inch pipe. Drillseveral l/4-inch holes above the jet point a distance of 1 to 2 feet. A thaw-line pipe projects amaximum of 2 feet through the head of the drive point.

Pump a water jet through the thaw-line pipe during drilling operations. Suspend the pipe on asimple chain hoist and slowly move the pipe up and down. The thaw-line pipe will penetrate thesediments ahead of the jet point. When the thaw-line pipe is about 2 feet ahead of the jet point,retract the pipe. The casing is driven as far as it will go; repeat the process. Use water no warmerthan 40oF in this process. Jet-drive drilling proceeds about three times as fast in permafrost as inthawed ground. See Figure 9-2 (page 9-2) for a rig you can use in Arctic well drilling. Figure 10-2(page 10-4) shows a jet-drive point you should use with the rig.

For depths of 100 feet or less, one man operating a rig can jet drive about 28 feet per day infrozen ground. If the ground is thawing, the footage per day is reduced. The well can yield 40gallons of water per minute from a 2-inch well equipped with a suction pump with less than 20 feetdrawdown. At a depth of more than 100 feet, jet-drive drilling becomes rather slow and difficult.Therefore, try to limit jet-drive drilling to the southern portions of the permafrost zone.

d. Drilling Fluids. The fluid used in drilling through permafrost must remain in a liquid stateduring drilling operations and must not contaminate possible water sources. You can eliminatepossible contamination through pumping. When using mud, try to keep the mud from freezing byadding chemical agents such as aquagel, gel-flake, barite, fibratex, smentex, micatex, and impermex.Be careful during periods of excessive permafrost thawing. The hole could slough during drilling.Do not heat the drilling fluid. An increase in the viscosity of the drilling mud will result in a decreasein mud flow, eventually causing freezing or sticking of the bit.

Brine, as a drilling fluid, is not ideal in permafrost areas because it promotes contaminationand excessive thawing. It could corrode the drill string, rig, and pump and cause a skin rash onpersonnel. Use brine sparingly, when required. In normal water-well drilling, you develop the wellby pumping after drilling, which clears the well of brine. A suitable brine solution would be 35pounds of rock salt mixed with 53 gallons of water. In the Arctic, 100 pounds of rock salt is amplefor drilling a 15- to 20-foot hole. (Figure 10-3, page 10-4) shows the specific gravity of drillingfluids when using salt additives in mud-drilling operations.) You must clean drilling equipmentafter using brine.

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CAUTIONAdding salts to drilling fluids

will reduce the viscosity,

e. Air Rotary Drilling. This is the preferred drilling method forintermediate- or large-depth wells if you have the equipment. Youdo not have to take the same precautions as with rotary drilling.

f. Well Installation and Completion. You can use some of thesame installation and development methods in cold climates as youdid in warm climates, with some precautions. Try to minimizeprolonged contact of surface water with any permafrost. Doing sowill avoid freezing in the hole or thawing and sloughing thepreviously frozen wall and the need to redrill. You can use thesingle-string method to install screen and casing together for wells inrock-like permafrost because disturbance is minimal.

The potential for water freezing after the well starts routineproduction should be reviewed. You could insulate the well bycentering a regular well casing in an oversized drill hole and bypacking the annulus with dry sand through the permafrost interval.You could then fit the well for continuous rather than intermittentpumping.

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Chapter 11Auxiliary Activities

11-1. Exploratory Drilling.

a. Geological Exploration. Use the same drilling methods for subsurface geologicalexploration as for standard well drilling. However, you will need special accessory equipment. SeeTable 11-1 for drilling methods and material samples. Auxiliary equipment for exploration drillingmay include solid and hollow-stem augers, sampling tubes, core barrels and bits, crackerjack bits,wash casing, and bailers. All the equipment is effective for sampling but varies for exploratorydrilling, depending on conditions. In shallow depths, use augers. However, auger samples aredisturbed and are not suitable for strength determinations. The samples can provide data such assoil type, water content, layer thickness, and changes in formation.

Use a rotary or a down-hole drill for depths beyond an auger’s range. Use these methods toobtain data for placing bridge abutments and structures and for determining the location, depths,and bearing stratum for other structures such as foundations, piles, dams, and underground facilities.You may have to drill boreholes to reach the materials that have good bearing capacities, to establishsoil and bedrock profiles, and to reveal flaws in rock formations. You may perform the samewell-drilling procedures for several tasks. When drilling, be swam of water occurrences and wheredrilling fluid loses circulation. These signs could indicate flaws in the rock. In shallow depths, usethe jetting method to obtain the same information.

b. Logging Techniques. In exploratory drilling on military installations or major facilities, ageologist will often be assigned to conduct the logging at the rig. The geologist provides directionson objectives and assistance on methods of sampling. Inexpedient field operations, the driller mayhave to serve as a technician and make all observations and logs.

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The driller should log each borehole regarding the depth reached and material taken. For fieldlogging of unconsolidated materials, use the Unified Soil Classification System in FM 5-410 forconsistency and compatibility of terms. The driller may have to rely on initial visual examinationof cuttings to describe the formation being penetrated.

c. Drilling Action. The driller should recognize changes in earth formations by the actions andsounds of all well-drilling equipment. For example, a change in pump circulation could indicatean aquifer. The driller should include such information in the log.

11-2. Sampling Soil and Rock. A valuable source of geologic and hydrologic information iscuttings from the penetrated rock. Handle these cuttings carefully. Collect samples from variousdepths to obtain the complete lithologic character of the formations penetrated. Use the coringmethod to take samples. With this method, you extract a solid piece of the formation. However,you can achieve the same results by carefully collecting loose cuttings.

a. Rotary Cuttings.

(1) Method. Examine the cuttings deposited in the return ditch or around the collar of the holeto determine the material the bit penetrates. If you are digging a deep well, take a sample every 5feet. If you are digging a shallow well, take samples at shorter intervals. Hoist the bit about 1 footoff the bottom, and rotate slowly while the mud circulates at full volume. Continue until the holewashes free of drill cuttings. Resume drilling for another 5 feet, raise the drill pipe slightly, and letthe mud circulate until it is clean of drill cuttings. If you use this procedure, the mud is screenedcarefully as it flows in the return ditch. You can obtain samples to identify the different beds.

(2) Contamination. Soft formations have a tendency to cave in and add extra materials to thedrilling fluid. When the drilling mud circulates, this material comes to the surface and contaminatesthe sample. Material from the upper formation can also contaminate the sample when drilling mudis not heavy enough to cushion the impact of the drill pipe against the walls of the well. You caneliminate much of the contamination if you make the mud pits large enough to ensure the settlingof all the particles of the cuttings before the mud circulates into the hole. If you want anuncontaminated sample, stop drilling and continue circulation until all cuttings are washed to thesurface. Clean the ditch, proceed with drilling for a few inches, and catchall the cuttings that washout. This sample represents the material drilled, provided the fine sand and silt are not carried intothe settling pit in the drilling mud.

b. Depth Determination. Determine the depth of a sample by measuring the lag time, whichis the time it takes for material to reach the surface. Lag time depends on--

Size of the hole.Condition of the hole.Type of formation penetrated.Type and viscosity of the mud.Actual depth of the hole.

You can measure lag time by placing material such as cut straw into the intake drilling mudpipe and recording the time it takes for the material to math the surface. Or, you can--

Stop the drill.

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Circulate the mud until it is free of cuttings.Drill down a few inches.Stop drilling and measure the time required for the cuttings to reach the surface.

The last procedure has the advantage of furnishing an accurate sample of the formation at thedepth of the bit. Use the procedure when you want very accurate formation samples.

c. Undisturbed Soil Samples. To collect these samples, advance the hole using a rotary orauger rig to a position just above the sampling interval. Clean the hole in the dry (when using anauger) or by flushing (when using a rotary rig). Recover the soil sample using either of the followingmethods:

(1) Push-Tube Method. With this method, you can use thin-wall, fixed-piston samplers in verysoft to stiff clays, silts, and sands that do not contain appreciable amounts of gravel. Use 5-inch-diameter sample tubes for all clays and silts that you can remove from the tube and keep in anundisturbed state. Some very soft clays and silts will not support their own weight, so you will notbe able to remove them in an undisturbed state. You can take samples of these soil soils with either3- or 5-inch-diameter sampler tubes. Seal the sample in the tube with expanding packers. Generally,a 3-inch-diameter sample of clean sand is sufficient.

Before sampling, chuck the drill rods in the drill rig with the drive mechanism raised to itsmaximum height. Doing so prevents the weight of the drill rods and sampler from bearing on andpossibly disturbing the sampled material. Rotate the piston-rod extensions to the right until thepiston-rod clamp or locking mechanism in the sampler assembly is released. Clamp the piston-redextensions to the drill-rig mast. Place a mark on the piston-rod extension where it emerges fromthe drill rod. Marking the rod will help you determine the exact length of drive. The sampler isready to push. The capability of the drilling rig to perform a continuous, smooth push limits thelength of the drive.

In noncohesive soils below the water table, the vacuum caused by the piston can cause pipingof the sample if the drive length is excessive. Samplers 24 to 30 inches in length are reasonable.The most satisfactory method of pushing an undisturbed sampler is with the drive mechanism(preferably hydraulic) on the drill rig. The rig must be firmly anchored to prevent the reaction ofthe drive from raising the rig and the sampler piston. Screw-type earth anchors are sometimes used.You must advance the sampler in one continuous push at a uniform rate. Do not rotate the samplerduring the drive. If the drive is interrupted, do not restart it. Adhesion and friction develop betweenthe sample and the tubing wall during an interruption. Restarting the drive will result in increasedpenetration resistance and disturbance of the sample. Withdrew the sampler, advance and clean outthe hole, and make a new sample drive.

(2) Core Method. If the sample material contains gravel or is too hard for a thin-wall sampler,use a double-tube core barrel or a Denisen sampler. These barrels are commonly used in obtainingsamples of very stiff, brittle, dense, or partially cemented soils and of soft, broken, fissured, or friablerocks. Use the following procedures for this method:

Step 1. Lower the core barrel to within a few feet of the bottom of the hole.Step 2. Circulate the drilling fluid to remove any excess cuttings that may have settledto the bottom.

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Step 3. Lower the core barrel to the bottom. Rotate and force the barrel downward at auniform rate.

If the soil erodes easily and the inner-barrel shoe will penetrate the soil under the pressureexerted on the core barrel, the inner-band shoe should extend below the cutting teeth of the outerbard. If this does not occur, use a shorter shoe that has a cutting edge even with or slightly abovethe cutting teeth of the bit. Adjust the rotation speed and the advance rate to ensure that the bitpenetrates continuously. If the bit advances too rapidly, it will become plugged and grind away thecore. If the bit advances too slowly or intermittently, the core will be exposed to excessive erosionand torsional stresses. Use a rotational speed of 50 to 150 RPM for most soil coring.

You must control the drilling-fluid pump pressure and flow when removing cuttings. Too muchdrilling-fluid pressure and flow will erode the core. Too little drilling-fluid pressure and flow willallow the cuttings to enter the core barrel, along with the core, and plug the bit. Try to useexperienced personnel to regulate the bit pressure, speed of rotation, and drilling-fluid pressure.However, you might have to experiment due to the variety of core barrels and drilling fluids andvariations in soils.

d. Rock Core Samples. You may recover undisturbedcore samples from hard rock formations with therotary-drilling rig. As with other sampling methods, coredrilling requires special auxiliary equipment and procedures.The diamond core bit and double-tube core bard are basicequipment (Figure 11-1 ). The assembly consists of an outerrotating tube or barrel attached to a core barrel head at the topend and the diamond drilling bit at the bottom. An inner tubeand core lifter receive and hold the sample stationary withinthe rotating assembly during drilling. Drilling fluid circulateddownward between the inner and outer tubes and the sampleremain protected. To take samples:

Lower the core barrel and bit into the boreholethrough the hollow drill rod.Start circulating the wash water before the corebarrel reaches the bottom of the hole to preventcuttings or sludge from entering the core barrel atthe start of coring.

The optimum rotation speed of drilling varies with thetype of bit used, the diameter of the core barrel, and the kindof material to be cored. Excessive rotation speed will result in chattering and rapid wear of the bitand the core will break. Low speed results in less wear and tear on the bit and better cores but lowerrates of progress. In medium to hard rock, use 300 to 1,500 RPM for diamond bits and 100 to 500RPM for metal carbide bits.

The advance rate of the coring bit depends on the material’s firmness, the downward pressureapplied on the bit, and the rotation speed. The driller must carefully adjust the pressure. Too muchpressure causes the bit to plug and to shear the core from its base. Bit pressure is controlled by a

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hydraulic or screw feed on the drilling machine. The weight of the drill-rod column seldom exceedsthat of the optimum bit pressure for coring medium and hard rock. You may have to apply additionaldownward pressure.

11-3. Installing Monitoring Wells. These are small water wells used for measuring water level,estimating well yield, and taking samples for quality analysis. These wells are drilled next topermanent wells at specified intervals.

a. Safety. Before installing a well, the safety of the drill crew and impact of drilling on theenvironment must be considered, especially in areas containing hazardous wastes. Potentiallyhazardous categories are chemical wastes and residues, flammable wastes, explosives andexplosives wastes, biological materials, toxins, radioactive materials, and harmful secondary vapors.Drilling crews may need protective clothing and respirators while working in such areas.

b. Requirements. Well-drilling equipment is suited for installing monitoring wells. Use thehollow-stem auger for boring clean holes while simultaneously supporting the borehole wall duringinstallation. Some piezometers use stock-porous well points. However, the installation methodsare quite similar. Be careful when taking samples for water pollution testing so that contaminationis not caused by the installation process.

c. Installation.

(1) Materials and Construction. Casings and screens can be mild steel, stainless steel, PVC,or chemical-resistant plastics such as teflon. Casing ends are threaded for tight couplings.Monitoring wells have a casing, screen, filter pack, and grouted intervals similar to water wellsexcept smaller. A 2-inch casing is the most common. Filter-pack sand should be just coarse enoughto stay outside the slotted semen. You can use bentonite pellets above the filter-pack and screenedinterval to seal the annulus and prevent water from leaking downward into the sampled stratum andcontaminating well intake. Make sure that all materials used in the well are sterilized, including thedrill rig.

(2) Procedure. To install a monitoring well--

Drill the hole about 1 foot below the position of the screen bottom.Place 1 foot of filter-pack sand in the bottom. Insert casing and semen (single-string)and center in the hole.Slowly add filter-pack sand while tapping and twisting the string to settle sand firmly.Continue falter-pack addition upward to at least 1 foot above the screen.Add bentonite pellets to the annulus above the filter pack for at least 2 feet. Seal theremainder of the annulus to the ground surface and grout in a protective collar.

11-4. Supporting Construction and Demolition. Support for drilling operations for aconstruction or demolition unit is an expedient mission. The supported unit determines drillingrequirements. A support mission is used as an alternative to mobilizing and fielding a separatedrilling operation.

For construction support, you can use a water-well rig with supplemental equipment for rockexcavation. You will need bits designed specifically for drilling rock rapidly without sampling.Rock bits include button bits used in down-hole drilling and tricone and other hard roller bits for

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rotary rigs. Rock-drilling applications might include foundation preparation, road cuts, andweapons pits.

For demolition support, a demolition specialist will provide specifications and guidance forpreparing area for emplacing demolitions or munitions. For information regarding safety whenusing explosives and demolitions, see FM 5-250. You should use the rotary rig and special bits forexpedient drilling and for placing demolitions. In soil, auger bits are ideal for shallow depths. Theauger has large-diameter capabilities that may be necessary for placing large charges. Thedemolition specialist will describe techniques for handling equipment and accessories duringemplacement. You can provide information about cavities and joints in formations that couldadversely affect demolition and about the position of the water table, which could be important indry versus wet conditions.

WARNINGHandle and use explosivesand demolitions properly.

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Appendix AWater Detection Response Team

A-1. Concept. In a combat environment, well-drilling production supplies the water requirement.Groundwater sources must be located quickly before committing well-drilling teams. Terrain teamsassigned to theater-, corps-, and division-level units make recommendations on well-drilling sites.If the geographic information the military provides the terrain teams is insufficient, terrain orwell-drilling teams determine well-drilling sites by best-guess methods. Also, terrain teams are nottrained or equipped in groundwater detection techniques. Because of these limitations, the WDRTconcept was developed to increase the overall effectiveness of well-drilling operations.Professionals and state-of-the-an equipment help accomplish the roundwater detection mission.

The subsurface WDRT consists of US government personnel who support military well-drillingoperations by performing groundwater detection. Civilian contractors may also be used. TheWDRT provides technical skills in remote sensing, geophysics, geology, and hydrology. TheWDRT currently consists of on-call federal civilian employees who respond within 48 hours to arequest to assess the subsurface hydrological situation any place in the world. Plans for on-callmilitary personnel are also being developed. The team recommends drilling sites that have the bestpotential for producing water to meet tactical requirements. Specialists are drawn primarily fromthe Corps of Engineers. Other government organizations, such as the United States GeologicalSurvey (USGS), participate when needed. Corps of Engineers’ organizations include the--

US Army Corps of Engineers Topographic Engineering Center (TEC).US Army Corps of Engineers Waterways Experiment Station (WES).Transatlantic Division (TAD).Mobile District, Savannah District, and other Corps’ Districts.

A-2. Organization. The WDRT consists of four functional elements: data base, remote sensing,supporting specialists, and geophysical. The TEC-Terrain Analysis Center (TAC) manages WDRTand provides leadership for the data base and remote sensing elements. The geotechnical laboratoryat WES provides leadership for the supporting specialists and geophysical elements. The supportingspecialists consist of civilian personnel who are geographers, botanists, hydrogeologists, foresters,well drillers, and area experts. A working team is selected and mobilized within 48 hours of avalidated tasking. The team may convene at the TEC-TAC to begin work by reevaluating data andimagery for the area of interest. The knowledge of the team and available information may besufficient to identify areas with high potential for developing water sources. Additional information,such as data from remote-sensing systems and hydrogeologic data, may be acquired from othersources.

A-3. Deployment. If data is still insufficient, WDRT will select and specify areas for conductingfield reconnaissance and geophysical surveys. Depending on mission requirements, a team maydeploy before or with the well-drilling team to assist with site selection and well design. Teammembers contact host-nation groundwater experts, evaluate any existing local groundwater sources,and conduct detailed hydrogeologic reconnaissance of areas previously identified as high potentialwater sources. The geophysical element of the team has the capability to conduct electricalresistivity, seismic refraction, and other geophysical surveys to assist in this field work. Once thewell drillers begin drilling, the supporting specialists can assist with well design, drilling expertise,

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and on-site geologic support. On-site geologists assist in logging and interpreting cuttings from thewell and with down-hole geophysical logging, when necessary. Down-hole logging is crucial inidentifying the highest water-producing zones during rotary mud drilling.

Subsurface geophysical surveys take time. If the geophysical element of WDRT deploys,enough lead time must be allotted for the team to conduct surveys. Planners overseeing contingencyplans should include WDRT work in their plans. Much of the work can be done before drilling byspecifying areas of interest so that data and imagery can be collected, analyzed, and placed on file.Planners should inform WDRT of the following:

Size of unit to be supported.Type of unit.Quantity and quality of acceptable water.Duration of requirement.

The WDRT usually deploys on military cargo aircraft with detection equipment packages ofup to 1,000 pounds of geophysical equipment. Once deployed, WDRT maintains this equipment,shipping it back to the owning agency for contract repair, if necessary. For seismic work, WDRTmay use small explosives (some of which may be standard military block explosives). Theexplosives are binary in nature and are mixed in the hole before detonation. The area commandersupports the WDRT with logistical and administrative support to include transportation, shelter,medical support, communications, food, water, and other classes of supply.

A-4. Operational Concept and WRDB. Army commanders or staff officers who require thepotential well-site locations should contact the supporting Army Engineer Terrain Team. This teamevaluates available data, especially the data supplied from the WRDB. The TEC-TAC is responsiblefor producing and maintaining the WRDB. The WRDB provides information on quantity, quality,and availability of water resources worldwide on an areal or point basis. This information helpscommanders make water-support logistics decisions and supports the Defense Mapping Agency’s(DMA) terrain-analysis program. The data base includes hard-copy thematic overlays (1:250,000scale base maps) that show the location, quantity, quality, and accessibility of existing waterresources, surface water supplies, and potential groundwater sources in selected arid regions inSouthwest Asia. The terrain team evaluates the database and responds directly to the requester, ifsufficient data is available. If no data is available or if more information is needed, a WDRT couldbe formed. The terrain team sends a request for assistance in locating groundwater supplies throughArmy Command channels to the US Army TEC-TAC. The WDRT manager at TEC-TAC designsa team from the on-call roster.

The chain of command for other components from unified or specified commands to requestdata is the Terrain Team of the Army component command or through command channels, JointChiefs of Staff (JCS), and DA. Locating and evaluating water supplies in an area would beconducted in an integrated systems manner, beginning with data-base querying and followed byexamining imagery and maps. The support command would decided which areas needed additionalsurveys. A WDRT may be deployed to conduct field geologic reconnaissance and geophysicalsurveys. Geologic reconnaissance will often be conducted without actual geophysical surveying.All available information, including field reconnaissance, will be used when categorizing potentialwell-drilling sites for the supported unit.

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A-5. Water Resources Overlays. The product of WRDB is a set of three transparent overlayskeyed to standard 1:250,000 scale Department of Defense (DOD), Joint Operations Graphics (JOG)topographic maps. The overlays provide the most current information for existing water-supplyfacilities, surface-water resources, and groundwater resources. The three overlays should alwaysbe used together to determine the water-supply potential of the area.

a. Existing-Water-Supply Overlay. An existing-water-supply overlay displays all knownman-made or improved facilities except for surface water bodies larger than 0.25 square kilometeters,canals, wells, springs, and qanats. This overlay also shows the location, capacity, and quality ofwater in existing production, distribution, and storage facilities. These facilities includedesalination, waste treatment and other purification plants, storage facilities, pumping facilities,pipelines, and miscellaneous supply facilities, such as ice-making and water-bottling plants.

b. Surface-Water Overlay. A surface-water overlay supplements the map and depictssurface-water resources, such as perennial water bodies (lakes and reservoirs), streams and rivers,dams, canals, and surface-water access areas. The overlay will contain information, if available,on water volume, flow rates, quality, and seasonality of water.

c. Groundwater Overlay. A groundwater overlay concentrates on groundwater potential. Ifexisting facilities cannot meet field water-supply needs, planners should use the surface andgroundwater overlays to determine where and when to drill water wells. If planners decided todevelop a water well, they should look at the information on the groundwater resources to help sitethe well. The drilling unit should also have this information to execute a successful completion.Whenever possible, the WDRT should assist by recommending specific drilling sites.

Military terrain analysts and well-drilling planners use the groundwater overlay to identify areasof groundwater resources. Using the overlays greatly increases the potential of siting anddeveloping successful water wells. From the overlay, areas of greatest groundwater potential canbe determined, along with the expected characteristics of the aquifer and overburden (material tobe drilled through to reach the aquifer).

d. Overlay Symbols. Potential water sources, where a point feature is located, are depicted bysymbols and include water wells, well fields, springs, and qanats. Symbols that appear on theoverlay with an adjacent number are keyed to a table with additional information. The areas ofpotential groundwater development are designated as Good(G), Marginal(M), Poor(P), or Unsuited(U). Areas of similar potential groundwater development may be further subdivided and designatedwith number suffixes such as M 1 and M2. Each potential area is keyed to a characteristics tableprinted in the margin of the overlay. These characteristics describe the potential yield of a well,depth to aquifer, aquifer thickness, water quality, overburden materials, and aquifer materials. Eacharea designated will have a set of groundwater characteristics associated with them. Thecharacteristics are given a numeric code that places them in one of four classes.

The rock types listed under overburden materials and aquifer materials should be consideredonly representative of the properties and not exact geologic descriptions. The driller can expect thehardness of the overburden to increase as the class number increases from 1 to 4. Aquifer-materialclasses indicate the more favorable aquifer in terms of yield and ease of drilling; the greater thenumber, the less favorable the aquifer. Sand and grovel aquifers consist of unconsolidated materialswith a large percentage of unfilled pore space. These aquifers are usually the best regarding yield

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and ease of drilling. Igneous aquifers are usually the largest and have the least amount of porosityand hydraulic conductivity and may be tough to drill through. Sandstone and limestone aquifershave properties between sand and grovel and igneous aquifers. If a limestone aquifer is cavernousand is expected to yield large quantities of water, the analyst preparing the overlay could rate theaquifer as a 2. This rating indicates that the aquifer material is better than the 3 rating normallyassigned to limestone.

A-6. Potential Drilling Areas. The following are reasons for areas to be eliminated or marked asunsuitable well-drilling sites:

If an aquifer is more than 1,500 feet deep, because military well-drilling machines cannotreach that depth.If no significant groundwater exists.If successful well completion is unlikely because of overburden materials, limited aquiferextent, or groundwater barriers restricting water flow.

Besides map legends, Supplemental lnformation should include detailed statements on seasonalgroundwater fluctuations, bacterial contamination, geology, and other pertinent information.Feature, with numbered symbols on the overlay, are entered into a Potential Water-Data Table.The numbered features include information on the following:

Well location.Well yield.Water quality.Well depth.Overburden and aquifer materials.Well use.Water-chemistry data.Water fluctuations.Feature names.

Numbered features on the overlay may also be keyed into a WRDB Analyst Report Form-RecordCharacteristics form that allows for the recording of particular technical information on the feature.Information such as construction and design of existing wells, pumping test results, and other datathat will aid in the design of new wells or assist in the maintenance of existing wells should beincluded. Most overlays are classified SECRET or CONFIDENTIAL. To order overlays, write toUS Army Topographic Engineer Center, ATTN: CETEC-TC-H, Fort Belvoir, Virginia 22060-5546,or call DSN 345-2921 or commercial (703) 355-2921.

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Appendix BNavy Well Drilling

B-1. General. The Naval Construction Force (NCF) Seabees, as part of their primary mission, aretasked to provide water-well-drilling support for the Marine Corps. Doctrine for this support is inOH13-4/NWP 22-9. Each naval mobile construction battalion (NMCB) table of allowances (TOA)includes four water-well-drilling technicians (NEC 5707) and well-drilling equipment and materialsto develop water wells from deep subsurface aquifers. To accomplish the well-drilling missions,well-drilling teams deploy from an NMCB by land, air, or sea.

B-2. Equipment. The NMCB TOA includes one International Standards Organization (ISO)air-transportable water drill (ITWD) (Figure B-1), one 750-psi/300-cfm air compressor, and two1,500-foot well-completion kits.

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a. The ITWD. This machine replaces the LP- 12 1,500-foot well-drilling machine and thesemitrailer-mounted Portadrills, models 501 and 521. The ITWD is an all-wheel-drive,self-propelled rig that can be shipped in a standard 8- by 8- by 20-foot IS0 shipping container. TheITWD can also be shipped on a C-130 or larger aircraft without disassembly. The machine is anall-hydraulic, top-head drive unit with a telescoping mast capable of employing standard 20-footdrill steel. The ITWD has a top speed of 10 miles per hour (mph) and is not designed forover-the-road mobility. It is lightweight, highly mobile, and suitable for rapid deployment withFleet Marine Force (FMF) engineer units. The machine is compatible with the Service LogisticalVehicle Systems (LVS). See Table B-1 for specifications on the ITWD.

The ITWD is capable of mud and air rotary drilling, rotary percussion, or down-hole hammerdrilling, using an auxiliary air compressor. A mud pump, water-injection pump, in-line oiler, fourcomer-mounted leveling jacks, fore and aft pintle hooks, utility hoist, driller’s station, and driver’sstation are mounted on the ITWD. The ITWD is deployed with a kit that includes lightweight drillsteel, drill collars, tricone bits, down-hole air hammer, and miscellaneous subs and adaptors fordrilling to a depth of 1,500 feet. Because of the various drilling capabilities, the ITWD can drill inany geological formation. If drilling requires the air compressor, it is brought to the site with thedrill rig or delivered by a support vehicle. For mud-drilling operations, teams need a water truckand the equipment to dig the mud pits.

b. Air Compressor. One wheel-mounted, diesel-engine-driven, 750-cfm, 300-psig aircompressor is included in each NMCB TOA for performing down-hole hammer drilling techniques.The ITWD is capable of towing this air compressor. The ITWD does not have on on-board aircompressor.

c. Well-Completion Kit. Each NMCB TOA includes two 1,500-foot well-completion kits.Materials in these kits are considered consumable project materials. The kits are used to developand complete a well. The supported unit is responsible for replacing the materials in the kits.

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Appendix CAir Force Well Drilling

C-1. General. Air Force well-drilling teams are organized and assigned according to Air ForceInstruction (AFI) 10-209. This publication outlines the organizational concepts and capabilities ofthe Rapid Engineer Deployable, Heavy Operational Repair Squadron (RED HORSE). Thissquadron provides the Air Force with a highly mobile, self-sufficient, rapidly deployable,civil-engineering, heavy construction and repair capability. The Air Force headquarters controlRED HORSE. Welldrilling units are assigned as a special-skills team to an operational REDHORSE unit. The unit provides the logistical support necessary to complete the well-drillingmission and the administrative support well-drilling teams require (Table C-l).

These units are classified for deployment using the following categories:

a. RH-1. This is an air-transportable RED HORSE echelon composed of 16 people. An RH-1team is ready for deployment 12 hours after notification. The squadron can perform advancedairfield surveys and site layout and can prepare for the orderly establishment and future developmentof a base of operations during contingencies.

b. RH-2. This is an air-transportable RED HORSE echelon composed of 93 people. An RH-2team is ready for deployment 48 hours after notification. The squadron can erect base shelters andperform limited earthwork and light base development during the initial phase of contingencies.Light base development includes installing aircraft arresting systems, expedient airfield matting,and essential utility systems.

c. RH-3. This is a RED HORSE echelon composed of 295 people. An RH-3 team is readyfor deployment six days after notification. Continental United States (CONUS)-based RH-3personnel usually deploy by air to the TO where they can be joined with pre-positioned RH-3equipment. CONUS-based RH-3 equipment usually moves overland to the TO. However, mostRH-3 equipment is air-transportable on a C-5. With equipment, an RH-3 team is capable ofperforming heavy repair, runway repair, facility hardening, and airfield expansion, to includeerecting relocatable facilities to support contingency operations.

C-2. Organization and Scope. Well-drilling teams are required to develop and provide adequatewater resources for deployed forces.

a. Capabilities. The well drilling teams should be able to do the following:

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Disassemble, transport, and reassemble the drilling rig.Set up the well drilling rig and support equipment.Drill a 1,500-foot, 6-inch diameter well.Drill with mud, air, and foam circulation.Drill with down-the-hole hammer.Drill in sand, soil, clay, rock, or other geological formations.Perform operator’s service checks and maintenance.Develop the well for connecting and interfacing with storage facilities andwater-distribution systems.

b. Requirements. The hazards and risks associated with water-well drilling require the higheststandards of training, proficiency, and safety. The following publications have specificresponsibilities that apply to water-well operations:

AFI 10-209.AFI 91-301.AFI 91-202.TA 429.Operations, maintenance, and repair manual for the assigned well-drilling rig.Repair parts manual.

c. Team Composition. A water-well-drilling team will be composed of a minimum of 12trained personnel. The team must provide a four-man, 8-hour shift, 24-hour drilling operation.Teams should be primarily 3E2X1 (construction equipment) personnel in grades E3 through E8.However, other Air Force Specialty Codes (AFSCs) should be considered, such as 3E4X1 (utilitiessystem specialist). The team must consist of 8 RH-2 and 4 RH-3 personnel. The officer incharge or noncommissioned officer in charge of the RH-2 or RH-3 team has theresponsibility for well drilling. The 12-man team should be broken down to 3 four-man teams.Special positions and duties are as follows:

Tool pusher (supervisor). Outlines the drilling program and sees that it is carried out.Driller. Operates the drilling rig.Derrick hand. Works in the mast, racks the steel, and so forth.Floor hand. Makes and breaks the connections, cares for all tools and equipment. Bothfloor and derrick hands carry out the mud program.

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d. Publications and Documentation. In addition to the publications listed in C-2b, eachsquadron will maintain, at a minimum, the following standard documentation and publication files:

TM 5-545.Ground Water And Wells (third edition).Ground Water Hydrology.Water Well HandbookDrilling Mud Data Book.Engineers Handbook.Percussion of Drilling Equipment Operation and Maintenance Manual. Catalog #500-2.

e. Equipment. The equipment in the RED HORSE units is not standardized and varies in makeand model.

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Appendix DElectrical Logging System

D-1. Logging Unit. The DR-74 Electrical Logging System has been designed for use in loggingshallow, vertical wells. It is a hand-operated unit. You manually lower and raise the well probe inand out of the well. The operator takes readings point b y point up the well bore and records thesereadings. The data is plotted on a logging form to get the graphical log needed for interpretation.When using the gear, you can get a spontaneous potential (SP) curve and three normal and twolateral resistivity curves.

a. Well Probe. The well probe consists of one brass current electrode and three lead-oxidepotential electrodes. Each electrode is internally insulated with epoxy resin, and each is connectedto the surface by a separate conductor. The potential electrodes are spaced at 0.25, 2.5, and 10 feetfrom the current electrode. The current electrode is drilled so that an insulated sinker rod can beattached to the probe with a leather thong if more weight is needed to carry the probe to the bottomof the well. With the resistivity instrument at the surface, the operator can read the SP in millivoltsand the resistivity in ohm-feet. The reel holds about 500 feet of cable. (An additional 500 feet ofcable can be attached to work at depths of 1,000 feet.) A test set is provided for checking theoperation of the instrument.

b. Resistivity Instrument. This instrument uses direct current and is of the null reading type.The instrument reads directly in ohm-feet. The use and operation of the various controls on theinstrument panel follow:

Galvanometer. This is a zero-centered micrometer. All operations of the instrumentinvolve returning the meter needle to the zero position.SP shutoff switch. This is a spring-return switch located in the upper left comer of thepanel. The switch automatically shuts off the l-1/2-volt C- battery (used in the SP circuit)when the instrument lid is closed.Probe selector switch. This switch is located directly below the SP shutoff switch on theunits modified for mud logging. When using the switch, the operator can select eitherthe normal probe with the 0.25-, 2.5-, and 10-foot electrode spacings or the mud probefor monitoring conditions in the mud pit or borehole.Self-potential potentiometer. This instrument balances out the SP that exists betweenany pair of potential electrodes. You must obtain a balance before making any resistivityreading. Balance is indicated when the galvanometers needle goes to zero. If you wantan SP curve, record the potentiometer reading. Each division is one millivolt; a full scaleis 1,000 millivolts.SP polarity-reversing switch. This switch is located directly below the SP potentiometerand shows the polarity of the particular cable electrode being used. When using theswitch, the operator can change the polarity of the injected voltage as required by boreholeconditions.Current switch. This is the ON-OFF switch located directly below the function switch;it is a momentary spring-return toggle switch. The spring-return is an automatic shutoffsafety feature.

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Function switch. This is the three-position selector switch located directly beneath thegalvanometers. The three positions are CUR (current), CAL (calibrate), and LOG(logging). Use the CUR position when checking the system to determine if you are usingthe correct amount of current. Use the CAL position when calibrating the instrument.Calibration is required at the start of the logging operation and after every 50 feet oflogging). Use the LOG position during the logging operation.Calibration adjustment. The CAL ADJUST is located in the lower right-hand comer ofthe panel and is used to zero the galvanometers when calibrating the instrument.Ohmmeter. This instrument is located directly above the CAL ADJUST and indicatesearth resistivity directly in ohm-feet. A reading at 0.25-foot NORMAL equals 1 ohm-footfor each division and 1,000 ohm-feet at full scale. A reading at 2.5-foot NORMAL equals10 ohm-feet for each division and 10,000 ohm-feet at full scale. A reading at 10-footNORMAL equals 40 ohm-feet for each division and 40,000 ohm-feet at full scale.Electrode selector switch. This five-position switch is located directly above theohmmeter. On the right side, it makes circuit connections for either the 0.25- or 2.5-footNORMAL arrangement. When the switch points straight up, the connections are for the10-foot NORMAL arrangement. On the left side, the connections are for the 0.25- and2.5-foot LATERAL arrangement, as marked. In the LATERAL arrangements, the10-foot electrode is the reference for both positions.Cable jack. This is the four-pronged receptacle located in the upper right comer of thepanel. The jumper cable from the logger cable case plugs into the jack thereby connectingthe instrument to the well probe.Potentiometer (POT). This is a black plug receptacle used to connect thesurface-potential ground wire (lead-oxide flag) to the instrument.CUR. This is a red plug receptacle used to connect the surface-current ground wire (steelstake) to the instrument.Test set. With the test set, you can check the instrument operation and condition of thebatteries without using the logging cable. The test set is normally kept in the base of theinstrument. To use the set do the following: plug the set into the cable jack, the red pluginto CUR, and the black plug into POT. Follow the usual logging procedure. You willhave little or no SP. The electrode selector switch may be in any of the NORMAL loggingpositions.

c. Power Supply. Three power sources of 1 1/2, 9, and 45 volts are requited. You can use aC -size battery for the 1 l/2-volt source and a 9-volt battery for the 9- and 45-volt sources.

d. Logging Cable. This cable used to lower the probe into the well. The cable has fourconductors that are made of copper-coated steel wire and are covered with a tough, durable 60percent natural-rubberjacket. The cable is very resistant to abrasion, is flexible at low temperatures,and has a high breaking strength of 320 pounds. The cable is marked every five feet with numberedmarkers.

e. Cable Reel and Reel Case. The reel case is made of drawn aluminum. The reel is made ofaluminum and PVC. The reel ends ride in bronze bearings attached to the reel case. Wheneverpossible, nonferrous metals have been used to construct the logging gear. Before removing or

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installing the reel, unreel the cable to lighten the reel. To remove the reel from the case, unscrewthe six screws from each bearing block and carefully lift the reel and bearings from the case.

f. Extender Cable-Reel Assembly. Use this cable when logging past 500 feet. The assemblyhas an S stamped on the flange to which you mount the jumper connector. This cable must be usedfirst. When you reach the 500-foot marker, attach the second waterproof connector to the cablereel. This connector will be located at the hub of the cable reel assembly. The second cable is thenconnected to the instrument by means of the jumper.

g. Surface Lines. Two small lengths of stranded-conductor, insulated wire are included withthe unit. The red wire has a plug on one end for connecting to CUR on the instrument panel and aclamp at the other end for fastening to a steel stake. (The steel stake is not furnished.) The blackwire has a plug on one end for connecting to POT on the instrument panel and a piece of oxidizedlead on the other end. If these lines become worn or broken, replace them with any 18- to 20-gaugestranded-conductor, insulated wire. These lines and reels are too large for the instrument cases, sothey are carried separately.

D-2. Types of Logging.

a. With the Normal Arrangement.

(1) Setting up Equipment. The equipment required to log a well includes the following:

Logging instrument.Logging cable.Surface-potential wire (black) with lead-oxide flag.Surface-current wire (red).Steel rod that is about 1/4 to 1/2 inch in diameter and 2 to 3 feet in length.

Use the following procedures when preparing to log a well:

Step 1. Plant the lead-oxide flag and the steel rod on opposite sides of the well about 75feet from the well. Bury the lead-oxide flag, which has been moistened with water andtamped, in a hole about 1-foot deep. Plug the black wire into POT and the red wire intoCUR on the instrument panel.Step 2. Connect the probe assembly to the logging cable only if the waterproof connectorsand their pins and sockets are clean. If the connectors do not mate easily after the pinsare aligned, apply silicone (spray or grease) to the surfaces. The connectors are matedproperly when you hear a pop.Step 3. Secure the locking rings.Step 4. Lower the probe to the bottom of the well and plug the jumper cable into thecable receptacle on the instrument panel. On units equipped with a mud probe, placeprobe selector switch NORMAL.

(2) Calibrating. To calibrate, place the function switch at CAL and the electrode selector switchat any NORMAL position, hold the CUR switch at ON, and zero the galvanometers needle byadjusting the CAL ADJUST knob. Calibrate at the start of each job and after every 50 feet of

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logging. If cannot zero the galvanometer, you may not have enough current flowing. See paragraphD-4, page D-6.

(3) Logging.

(a) Balancing out SP. With the electrode selector switch at 0.25 NORMAL, turn the functionswitch to LOG and zero the galvanometers needle b y adjusting the self-potential potentiometer. Thedial reading on the potentiometer is the SP in millivolts with the polarity of the probe electrode asindicated on the reversing switch. If you cannot zero the galvanometers, reverse the polarity switchand try again. If reversing does not work, see paragraph D-3 and paragraph D-4 (page D-6).

(b) Measuring resistivity. After balancing the SP, hold the current switch at ON and returnthe galvanometers needle to zero by adjusting the ohmmeter. Release the current switch. The dialreading of the ohmmeter is the resistivity for the 0.25-foot NORMAL electrode spacing. Turn theelectrode selector switch to 2.5-foot NORMAL and repeat(a) and(b). Multiply the dial reading onthe ohmmeter by 10 to obtain the apparent earth resistivity for this electrode spacing.

To obtain a log, the well probe must be below the fluid level in the well. When you pull theprobe out of the water, the resistivity instrument will go dead. To quickly check the fluid-leveldepth, turn the function switch to CUR and hold the current switch at ON, When you pull the wellprobe out of the fluid, the galvanometers needle will return to zero.

The 0.25- and 2.5-foot NORMAL readings are preferred logs for most wells. If you want anSP curve, the electrode selector switch should be in the 0.25-foot position. However, in a largeborehole or in an exceedingly high-formation resistivity, you may have to use the 10-foot NORMALposition. In the NORMAL position, the instrument is not directly reading. Use 40 as the multiplyingfactor.

To become proficient in the above procedures, use the test set and practice taking readings.The spacing between readings depends on the amount of detail being sought. For most situations,take readings every 2.5 feet. In 1- to 2-foot thick formations, take readings every 1 foot to 2 feetup the well born. In logging mud-filled or deep holes, attach a sinker rod to the probe so you canfeel the bottom of the well. When using metal, cover the metal with friction or electrical tape andattach the sinker to the well probe with a leather thong.

b. With the Lateral Arrangement. In areas that have highly resistive surface materials (desertsor dunes) or large and varying ground potentials (highly industrialized areas using largedirect-current generators), you may not be able to make a normal log. Use a lateral log to overcomethese difficulties.

The setup is similar to the NORMAL arrangement except you will not need the lead-oxidesurface electrode (POT). You can complete the current circuit (CUR) by attaching the red wire tothe well casing or any other good ground. The electrode-selector switch must be in one of the twoLATERAL positions. To complete the reading, use the procedure as for the NORMALarrangement. However, the meter does not provide a direct reading. For the 0.25-foot lateral, thefactor is 1.025 (essentially direct); for the 2.5-foot lateral, the factor is 13.33.

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D-3. Mud Probe (on Units Modified for Mud Logging).

a. Calibrating. Unit calibration is a rear panel adjustment and is adjusted for the mud loggerprobe furnished with the unit. However, the CAL ADJUST potentiometer will effect someadjustment to accommodate changes due to temperature and battery condition. If the rear paneladjustments are not tampered with and the galvanometers needle remains within + 2 minor divisionsof zero when calibrating the instrument in the CAL position of the function switch, the calibrationof the instrument will be + 10 percent of the obtained reading.

Unit checkout of the instrument in the mud mode of operation with the test set may be done asin the normal mode with the results obtained. Electrode switch must be in one of the followingNORMAL positions:

CUR position -at 10 divisions.CAL position - within + 2 divisions of zero.LOG position - reading on ohmmeter of about one-tenth the value marked on test set oras indicated on resistivity chart furnished with instrument.

Note: Self-potential potentiometer must beat zero.

b. Setting up the Equipment. Since the electrode array is contained within the mud probe, thesurface lines are not used. A special jumper makes the proper electrical connections between theunit and the cable reel. Use the following procedures for calibrating:

Step 1. Place probe selector switch to MUD.Step 2. Connect the mud probe to the 500-foot cable. Press the connectors until you heara pop, which indicates that the waterproof sealing surfaces are mated. Secure the threadedlocking rings.Step 3. Pull desired length of cable from the reel and attach the mud logger jumper tothe instrument and cable reel. Place unit in any of the NORMAL logging positions.Step 4. Pack the probe with mud or lower it into the borehole.Step 5. Place the function switch at CAL, energize the current switch, and make surethat the galvanometers needle is centered. If needle swings full left, place function switchat CUR and check for probe current. The needle should deflect about ten divisions tothe right of zero, indicating that about 1 milliampere (ma) of current is flowing. If younote a zero deflection, the probe electrodes have not made contact with material to bemeasured.Step 6. If you get proper indication at CAL or CUR, place the function switch at LOGand adjust the SP or the 0 on the galvanometers.Step 7. Energize the current switch while adjusting the ohmmeter potentiometer untilyou notice minimal or zero deflection of the galvanometers. If the current switch keepsenergizing, the galvanometers needle may start to swing to the left as an induced voltageis set up in the probe. You can verify this by turning the galvanometers needle back tothe right an equal distance as the left swing that shows up as an SP on releasing the currentswitch.

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D-4. Troubleshooting Procedures. The logging unit has a test set that you can use to check theinstrument’s operation independent of the cable assembly. If the instrument reads the correct valuefor the test set, then the instrument is functioning properly and the trouble is somewhere other thanin the electronics of the instrument. See page D-2 for operating instructions for the test set. Theelectrode selector switch must be in any NORMAL logging position.

a. Checking Batteries. With the test set plugged into the instrument, turn the function switchto CAL and try to calibrate the instrument. If you cannot calibrate the instrument, turn the functionswitch to CUR and check the current by throwing the current switch. If the current flowing is lessthan 8 ma, replace all six 9-volt batteries. Refer to battery voltage checking procedure to check thebatteries with a voltmeter. The following lists some common problems with the correctiveprocedures:

(1) Unable to Calibrate Instrument. This problem occurs because of insufficient or no currentflowing in the ground circuit. To correct the problem, check the batteries and replace them whennecessary. Check all lines and plugs for bad connections.

Sometimes insufficient current results from high resistance at the steel surface-currentelectrode. If the galvanometers shows less than 9 ma and you cannot increase the amount by rotatingthe CAL ADJUST knob, then the contact resistance at the steel stake is too high. Reduce theresistance by driving the stake deeper or pour water around it or double stake until you get an excessof 8 ma.

If you cannot get a minimum of 8 ma, the ground circuit is too resistive (a situation encounteredin areas having a thick cover of dry sand or where there is frost on the ground). To get a log in thiscase, use the lateral arrangement of electrodes with the CUR wires connected to the well casing.

(2) Fluctuating SP. This problem occurs when the galvanometers needle fluctuatesuncontrollably when the function switch is at LOG. To correct the problem, check the surface-potential reference (lead-oxide flag) to make sure it is buried in moist soil and that the wire is notfrayed or broken. If the SP fluctuates badly, stray ground potentials are the cause. This situationcan occur in highly industrialized areas. To correct the problem, use the LATERAL arrangementof electrodes.

(3) Unable to Zero the Meter with Self-Potential Potentiometer. To correct the problem,reverse the SP polarity switch. To zero the galvanometers, the injected voltage must be the correctpolarity. If reversing the polarity switch does not work, check the voltage of the 1 l/2-volt C-batteryand replace the battery when necessary.

Note: The SP polarity may change during the logging.

(4) No Meter Response to Self-Potential Potentiometer. If the instrument has not been usedfor a while, the SP shutoff switch could stick at OFF. Push the button up and down several timesto release the switch. Also, check all plug-in connections and surface lines, particularly the potentialsurface line and where it connects to the lead flag.

(5) Meter Deflection with No Connections to Instrument. This condition exists when waterhas entered the current switch causing an electrical connection to remain in the switch without theswitch being activated. To correct the problem, dry the switch by applying heat to the switch. Ifthis condition occurs frequently, install a rubber boot on the switch.

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Note: This condition is not normal. If you can effect proper calibration and operation of the unitwith the test set, then the instrument will operate properly when you activate the current switch.

b. Using a Voltmeter. Conduct the following checks with the test set:

(1) One 9-Volt Battery.

Place the voltmeter function switch at +direct current (DC) volts and the range switch atfull scale reading closest to, but no lower than 10 volts.Connect the red (+) lead to the positive (male) and the black (-) lead to the negative(female) battery terminals. Record this open circuit voltage.Place function switch at CUR or CAL mode, energize the current switch, and record thebattery voltage under load. The voltage should remain at or slightly below theopen-circuit voltage.Replace the battery if the voltage should continue to change value when the current switchis energized.

(2) Five 9-Volt Batteries.

Place the function switch at +DC volts and the range switch at full scale reading closestto, but not lower than 50 volts.Connect the red (+) lead to the exposed positive terminal (male) and the black (-) lead tothe exposed negative terminal (female) of the battery string. Record this open-circuitvoltage.Place the function switch at CUR or CAL mode, energize the current switch, and recordthe battery voltage under load. The voltage should remain at or slightly below theopen-circuit voltage.Replace all the batteries if the level should continue to change value when the currentswitch is energized.

In adverse or cold weather conditions, install an alkaline-type battery in the unit because thosebatteries have better voltage-cunent characteristics.

c. Calibrating the DR-74 Mud Logger (with a Known Salt Solution).

Place instrument in mud mode.Connect probe to unit.Lock SP potentiometer at zero.Place function switch at LOG.Put probe in known concentration of sodium chloride and distilled water.Take temperature of water sample.Clean probe in distilled water, when necessary.Refer to resistivity, concentration, and temperature chart to determine the resistivity ofthe sample known concentration and temperature. If in ohmmeters, multiply reading by3.28 to convert to ohm-feet. Set ohmmeter potentiometer to this reading and lock.Place function switch at LOG.

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Center CUR ADJUST potentiometer on front panel to center of travel.Energize CUR switch, momentarily, and the CAL ADJUST potentiometer marked log,which is on the circuit board on the back of the galvanometers, to zero the needle to thatposition when CUR switch is not energized.Place function switch to CAL. Rotate the CAL ADJUST potentiometer on same boredto zero the needle in the same manner as above (when energizing the current switch).Recheck the log position. If necessary, readjust both potentiometers until you get properreadings.

D-5. Maintenance. Keep all plugs, panel connections, and cable and reel case clean and dry.Moisture on the panel plugs or cable plug can cause current leakage and cause the gears to operateimproperly. When pulling the cable out of the well, wipe it clean. Do not let water accumulate inthe reel case.

a. 0f Resistivity Measurement. Required maintenance is cleaning and changing batteries. Thetest set will indicate when to replace the 9-volt batteries. Replace the 1 l/2-volt cell every twomonths. The battery box is at the bottom of the case. Lift the instrument panel to access the batteries.

When operating the instrument, be careful not to slam the care ohmmeter and self-potentialpotentiometer dials against their zero stops. When the dials are turned completely counterclockwise,they should read zero. If they do not, loosen the two setscrews, set them 90 degrees apart, and resetthe knob to zero. (To set the screws, use the allen wrench that is taped on the potentiometer.)

b. Of Cable and Reel Case. When handling the cable, be careful not to damage the insulation.Always clean the cable before storing it. Store the reel case in a dry place. Keep the reel case lidleft open until the cable is thoroughly dry.

D-6. Interpretation of Electrical Logs.

a. Preparation of the Log. When preparing the log, plot the 0.25-foot reading, NORMALarrangement at the depth you read from the marked cable. Plot the 2.5-foot readings about one footabove that point. You plot the readings in this manner because the cable markings have beenmeasured from the current electrode. For the LATERAL arrangement, plot the values as for theNORMAL arrangement. If you use the 10-foot NORMAL, plot the readings about 5 feet above themarked cable reading.

b. Significance of 0.25-Foot Spacing. The reading you get from the 0.25-foot spacing is greatlyinfluenced by the fluid in the well bore. The reading is only a fraction of the formation resistivit y.However, the short spacing lets you to see changes in resistivity with greater detail. With thiselectrode spacing, you can detect formations with a thickness of about 6 inches or more. Becauseyou can see more detail, use the 0.25-foot curve to pick formation boundaries.

c. Significance of 2.5-Foot Spacing. The 2.5-foot electrode spacing gives you the closest trueformation resistivity for wells with diameters up to 16 inches and for formations thicker than 5 feet.For larger diameter wells or thinner formations, the measured resistivity will depart somewhat fromthe true. For qualitative interpretation, this departure is not significant. Because the 2.5-foot curvegives you the formation resistivity, use it to identify the type of material penetrated.

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d. Significance of the Lateral Log. You get a lateral log by combining either the 0.25- or 2.5-foot electrode with the 10-foot electrode. Because the distance of the 10-foot electrode is largerthan the other electrodes, you can interpret the log as for the normal log after using the appropriatecorrection factors. For the 0.25-foot lateral log, the meter factor is 1.025. For the 2.5-foot laterallog, the meter factor is 13.33.

e. Interpretation of Resistivity Values. When interpreting the resistivity values, the followinggeneralities may apply: clays and shales will have low resistivity; sands, grovels, sandstones, andlimestones will have high resistivity; igneous and metamorphic rocks (granites and gneisses) willhave extremely high resistivity. The exact range of numerical values will depend on the following:

Type of earth material making up the formation.Degree of cementation of the formation.Water quality of the formation water.Porosity of the formation.Diameter of the well born.Resistivity of the fluid in the well bore.

Granular materials will have high resistivity compared to fines such as silt and clay; crystallinematerials (such as limestone or granite) will have high resistivity compared to the granular materials.The quality of the formation water will affect the measured resistivity. In general, the resistivity ofa formation will vary in an inverse proportion to the total dissolved solids. For example, if allconditions remain the same but the total solid content increases, the formation resistivity willdecrease. Hence a clean sand filled with salty water may actually have extremely low resistivity.

Porosity of the formation also has an effect on the resistivity. In the logging of chemicalprecipitates, such as limestone, changes in porosity may enable you to detect the water-producingzones. Increased porosity will lower the formation resistivity and hence in such material a lowresistive zone (where no shale is present) is indicative of increased porosity. This is then indicativeof possible water production.

In the midwestem United States, clean sand and grovel generally exhibit resistivity values of350 to 1,000 ohm-feet. The lower values apply to formations having water quality in the range of300 to 400 ppm total solids and the upper values apply for formation waters having 100 to 150 ppmtotal solids.

f. Selection of Formution Contacts. When selecting the formation boundaries, use the0.25-foot curve, when possible. The inflection point of the resistivity curve (the point midwaybetween changes in curvature of the resistivity curve) is used to mark the contact between differentformations.

g. Correlation of Electrical Logs. You can use the electrical logs to correlate formationthicknesses and depths from one well to another. For example, two wells within a few feet of eachother invariably will give identical electrical logs. When the wells are farther apart, you should stillbe able to recognize the correlation. Studying the changes (thickening or thinning of beds) couldbe useful for further exploration. In bedrock formation, correlation is possible with distances ofthousands of feet. However, such distances are the exception.

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h. Effect of Metal on the Resistivity Log. Because metal is a good conductor, its presence inthe measurement zone will cause a major decrease in the resistivity and make the log unusable fordetermining formation type. However, using metal could help locate steel in the well.

In making the log, the bottom of the well casing will be detected when the probe enters it. Theeffect on the curves will be that both fall off to extremely low values, 5 to 20 ohm-feet, and thenremain fairly constant. Where the casing is seated into very low-resistive shale, it may be ratherdifficult to determine the exact position of the casing by this method.

i. SP Curve. This curve shows a great deal of character and can be related to relative changesin formation permeability. When logging in freshwater horizons, the SP curve will usually befeatureless and provide little or no useful information.

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Appendix EBits

E-1. Maintenance. The rock drill bit (Figure E-1, A) is the least understood component in a drillingsystem. The parts of a drifter or down-hole drill undergo constant dynamic loading that can beaccounted for with design. However, this is not true with the bit. Drilling in rock may mean aradical change of hard consolidated rock to a broken unconsolidated seam. The characteristics ofrock-compressive strength, abrasiveness, and fracture pattern-are never consistent in eitherproduction or water-well drilling. Figure E-1, B shows drilling through various rock formations.Flushing passages (Figure E-1, C) must be well maintained and fairly deep to clean the hole. Asthe gauge of the bit is reduced by abrasive wear, many drillers forget to grind the slots deeper. Poorhole cleaning is a major cause of stuck drill string.

The following describes the areas to maintain on the bit for effective operation. Figure E-2(page E-2) shows the areas described.

Abrasion and poor hole cleaning will cause material around the exhaust hole to peen over.This action restricts the flow of air and causes even poorer hole cleaning. It is essentialto grind exhaust holes open for best results.On down-hole drilling (DHD) bits, always apply grease to the spline before assemblyin the chuck. On threaded bits, grease all shoulder and threaded areas.

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As a bit begins to wear, the face of the bit begins to look washed (worn away). The metalis washed at a faster rate than the carbide wears. The carbide should be ground until nomore than 3/8 inch protrudes from the metal surface. If carbide is allowed to projectfurther than 3/8 inch, carbide breakage is inevitable.Abnormal spline wear is usually caused by a worn chuck excessive feed force, or highRPM operation. By checking the bit for spline wear, you maybe able to prevent shankingof the bit, damage to the hammer, and loss of the hole.Although abnormal body wear or failure is not common in percussion drilling, check thebit body for fractures. By checking the body, you may prevent the loss of the bit in thehole. If barreling occurs, grind the bit body because the body of the bit should be keptin its original shape. Barreling results when a wear pattern occurs causing the diameterof the bit body to exceed the gauge diameter of the buttons.Check the striking end for excessive pitting. Pitting is usually caused by the presence offoreign material such as rock cuttings or use of rock drill oil with a high sulphur content.Drilling with a large amount of water may also accelerate corrosion on the striking end.A badly worn striking end is a sure sign that you should check the piston of the drill.Replacing the piston before breakage will usually save the cylinder.

You should recondition thecarbide insert or button (Figure E-3)to maintain its original shapethroughout its useful life. Most bitfailures involve carbide breakage orloss of carbide resulting fromimproper preventative maintenanceor drilling practices.

E-2. Failure. Carbide shear(Figure E-4, A) is the most prevalenttype of carbide breakage. Tungstencarbide is very strong incompression, yet is relatively weakwhen placed in a tensile or shear

mode. As the buttons begin to wear, they develop flat spots(Figure E-4, B). As these flats develop, the loading on thecarbide begins to move from its basically vertical positionor compression load to a horizontal position or shear load.This side loading or pinching (Figure E-4, C) of the carbidein the hole can ultimately result in carbide shear.

Figure E-5, A shows an overrun bit with severe flatspots. This condition will soon lead to button failure.Buttons must be ground to restore their original shape at

the first sign of a developing flat. High rotation speeds tend to accelerate the development of flatson the carbide. Although RPM will vary with local conditions, rotating the bit faster will not increasethe penetration rate but will increase the chances of shearing a carbide (Figure E-5, B).

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Progressive heat checking in the developed flats indicates excessive RPM. Small cracks(Figure E-6, A) develop on the face of the flat and if not reconditioned, breakdown of the buttoncontinues until it finally splits. The button then shears off and the effectiveness of the bit is lost(Figure E-6, B). A good rule of thumb is to rotate at the lowest RPM that permit smooth operation.

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Another condition that can result in carbide shear is drilling through bent casing (Figure E-7,A). A bent casing will cause the carbides to be pinched as the drill string passes through it and thecarbide breaks as a result. Also, when changing bits after starting a hole, do not put a larger bit intoan existing smaller diameter hole. Always measure bit gauge and use the larger bit first to preventpinching the gauge carbides (Figure E-7, B).

After many hours of drilling innonabrasive soft rock the carbide begins tofatigue. A network of fine cracks appearand small flecks of carbide break away(Figure E-8). The buttons have a polishedeffect with no flats, and there is minimumabrasive wear on the bit body. If notchecked, this will lead to furtherbreakdown of the carbide, side loading, andcarbide shear. To prevent this type offailure in soft formation drilling,reconditioning must be scheduled atintervals that do not exceed 10 percent ofthe overall life expectancy of the bit.

Popping of carbide inserts is a result of loose running. A carbide will pop clean from its socketif the drill string is not properly fed up in the hole (Figure E-9, A). This is most common inoverburden drilling or in broken and unconsolidated formations. A large amount of energy isproduced from the piston striking the shank in drifter drilling or the bit in down-hole drilling if thebit is not fed up to the rock. Instead of breaking the rock, this energy is retained in the bit and willcause the carbides to pop (Figure E-9, B). When body metal around the carbide becomes too weakdue to overrunning the bit without proper grinding, the buttons pop out (Figure E-9, C). This greatlyreduces the life of the bit.

—

Body metal is another type of bit failure. Figure E-10, A shows a condition called body wash(eroded body metal). Figure E-10, B shows the lip next to the button and the extent to which the

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button is protruding. The combination of a flat carbide and a large beam of exposed carbidegenerates side loading which fatigues the base in which the button rests. Figure E-10, C shows thatthe carbide and body have separated just below the rim of the socket while a fatigue crack hasdeveloped in the body metal. Cracks in the body (Figure E-10, D) can lead to entire pieces of thebit shearing off.

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FM 5-484/NAVFAC P-1065/AFMAN 32-1072

For optimum performance, introduce a bit to new rock regularity. If cuttings remain in thehole, the energy to break new rock is not transferred, putting undue stress on the bit, the drill, andthe drill string. Each component will undergo more unnecessary stress and will fatigue faster andfail earlier. Figure E-11 shows an extreme example of what will happen if air is not continually feddown the hole. This bit has been plugged solid by the cuttings.

If rotation is too fast, flat spots, heat checks, and shearingwill occur. If rotation is too slow, lopsided wear on thecarbides will occur. Figure E-12 shows a bit that has beenrotated too slowly. The button is barely out of the impressionit made with the previous impact, when it is struck again.Undue wear is caused on one side of the button, creating apoint on the carbide. When the point is sharp enough, itchips, or portions of the button break away.

E-3. Reconditioning. The following lists some suggested equipment necessary for proper bitreconditioning:

A bit-grinding stand and a vitrified silicon carbide wheel that is 1 inch by 1 inch indiameter and rated at 25,000 RPM.An I-R DIR DG121 grinder or its equivalent.Safety glasses, hard hat, ear protection, and gloves

You must restore the original shape of the button when regrinding. To come close to this shape,draw a pencil line down the center of the flat on the gauge button (Figure E- 13, A). Using the lineas a guide, grind the button on both sides, but leave the pencil line untouched (Figure E-13, B).Leaving the pencil line ensures that the reground bit carbide will be concentric to the bit shank.(When concentric, the carbides carry an equal share of the load.) Also, leaving the pencil lineprevents you from grinding away too much carbide, thus extending bit life. Finally, blend theuntouched line area (Figure E-13, C). When finished, the button should look almost new. FigureE-14 is a diagram of a reconditioned button. Although gauge buttons receive most of the wear,grind all of the buttons, if necessary, (Figure E-15, A, page E-8); grind the flutes (Figure E-15, B);check the blowholes (Figure E-15, C) and grind them back into shape (Figure E-15, D).

E-4. Rule of Thumb. In down-hole and drifter drilling, the most important factor contributing topoor performance and premature bit failure is operating the bit beyond the reconditioning point. Afixed guide outlining exact bit reconditioning intervals would be ideal. However, changing drilling

E-6

FM 5-484/NAVFAC P-1065/AFMAN 32-1072

conditions make the establishment of such a guide unrealistic. Therefore, establishing such intervalswill ultimately be determined on the job. Consider the following recommendations:

In hard abrasive rock recondition at the first sign of a flat on the button bit. A flat widthshould never exceed 1/4 inch.In soft or less hard abrasive formations, recondition before reaching 10 percent of theexpected life of the bit. This prevents alligator-type failures and ensures proper bit life.

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FM 5-484/NAVFAC P-1065/AFMAN 32-1072

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FM 5-484/NAVFAC P-1065/AFMAN 32-1072

GlossaryACE Assistant Chief of EngineersAF Air ForceAFI Air Force instructionAFP Air Force pamphletAFSC Air Force Specialty Codeair-foam-gel technique Adding foamer to a fluid

in the same proportions as clear water to get aricher, more stable foam.

air-lift method A pump-testing method that usesan air-lift pump,

air-line method A procedure to measure thewater level using an air line; the air line iscopper tubing or galvanized pipe that is longenough to extend below the lowest water levelbeing measured.

air rotary driling A well-drilling method thatuses compressed air as the circulating fluid.

alligatoring A network of fine cracks and smallcarbide flecks on a bit that appear after hours ofdrilling in nonabrasive soft rock.

alluvium Soils that are deposited by runningwater.

alt attitudeant-mound-like openings. See qanatAO area of operationsAPOD aerial port of debarkationAPOE aerial port of embarkationaquagel Commercial chemical agent added to

mud drilling fluid to prevent it from freezing.See also barite; fibratex; gel-flake;impermex; micatex; smentex

aquiclude Subsurface rock or soil unit, such asclay, shale, and unfractured igneous andmetamorphic rock, that does not transmit waterreadily and cannot be used as a water-supplysource.

aquifer Saturated rock or soil unit, such as gravel,sand, sandstone, limestone, and fracturedigneous and metamorphic rock, that hassufficient hydraulic conductivity to supply waterfor a well or spring.

aquitard A unit that retards or slows the passageof water.

AR Army regulationArk ArkansasARTEP Army Training and Evaluation Programattapuigite Commercially processed clay used for

drilling in brackish or salty water.ATTN attentionaugered well A well that is bored using hand-or

power-driven earth augers.AWWA American Water Works Association

backwashing Well-development method. Seealso jetting method; gravity-outflowmethod; pressure-pumping method;pump-surge method; surge-block method

ball-down method Installing screen using aspecial end fitting,

bail-down placement A method ofsimultaneously placing the gravel pack andinstalling the screen.

Barafos A white, granular sodium tetraphosphatethinner and dispersant added to drilling fluid toprevent mud from sticking to sand grains.

barite Commercial chemical agent added to muddrilling fluid to prevent it from freezing. Seealso aquagel; fibratex; gel-flake; impermex;micatex; smentex

barreling A wear pattern that causes the diameterof the bit body to exceed the gauge diameter ofthe buttons.

basalt An igneous rock that is a very productivewater bearer.

Glossary-1

FM 5-484/NAVFAC P-1065/AFMAN 32-1072

bentonite Commercially processed clay used fordrilling; bentonite forms naturally fromdecomposition of volcanic ash, consists ofaggregates of flat platelets, and contains sodiummontmorillonite, which is important in buildingviscosity.

body metal A type of bit failure.body wash Eroded body metal in bits.BOM bill of materialsboundary indicators Characteristics that are

indicative of local or regional groundwater flowsystems.

brass-jacket-type drive point Consists of aperforated pipe wrapped with wire mesh andcovered with a perforated brass sheet.

brass-tube-type drive point Consists of a brasstube slipped over perforated steel pipe for arugged construction.

cable jack A four-pronged receptacle located inthe upper right comer of the panel on theelectrical logging system.

cable-tool method A very slow drilling methodthat can be used to penetrate rocky soil ormoderately hard sedimentary rock; the drill usedin this method does not require large amounts ofdrilling fluid.

CAL calibrateCAL ADJUST (calibration adjustment)

Located in the lower right-hand comer of thepanel on the electrical logging system and usedto zero the galvanometers when calibrating theinstrument.

carbide shear The most prevalent type of carbidebreakage in bits

casing ring and slip A device used to suspend thecasing at the ground surface and for pulling pipefrom the hole using jacks under each side of thecasing ring.

catchment Formation whine impervious rockunderlies a zone of fractured rock or alluviumthat serves as a reservoir for infiltrated water; acatchment can be a special type of aquifer.

cathodic protection. See sacrificial anodeCB construction battalion

cc cubic centimeter(s)centrifugal pump A variable displacement pump

in which water flows by the centrifugal forcetransmitted to the pump in designed channels ofa rotating impeller.

cfm cubic foot (feet) per minutecfs cubic foot (feet) per secondcircular-orifice meter A device used to measure

discharge rates.circular-orifice method A procedure to measure

discharge rates using a circular-orifice meter.closed-well method A compressed-air method

that involves using compressed air to close thetop of the well with a cap and by arranging theequipment so air pressure can buiId up insidethe casing to force water out through the screenopenings.

cm cubic meter(s)compressed-air methods Rapid, effective well-

development methods. See also closed-wellmethod; open-well method

CON DET A wetting agent added to drilling fluidto increase the dispersion action ofpolyphosphates.

confined aquifer An aquifer that is completelyfilled with water and is overlaid by a confiningbed.

confining bed Aquiclude that exists betweenaquifers, water moves only within the aquifer.

consolidated deposit Rock that consists ofmineral particles of different sizes and shapes.

continuous permafrost A zone where permafrostwill be thick with no unfrozen ground. See alsodiscontinuous permafrost; permafrost

continuous-slot drive point A screen withhorizontal openings and one-piece weldedconstruction and contains no internal perforatedpipe to restrict the intake area.

CONUS continental United Statescore barrel A double-tube sampler used to collect

undisturbed soil samples in material that eithercontains gravel or is too hard for a thin-wallsample.

CPM critical-path method

Glossary-2

FM 5-484/NAVFAC P-1065/AFMAN 32-1072

crop irrigation Surface indicator that shows theuse of surface water or groundwater foragriculture.

CSS combat service supportCUR (current) A red plug receptacle used to

connect the surface-current ground wire to theinstrument.

current switch The ON-OFF switch locateddirectly below the function switch; the currentswitch is a momentary spring-return toggleswitch.

d depthDA Departmnt of the ArmyDarcy’s Law Principle that describes the flow of

groundwater.DC direct currentDenisen sampler, See core barrelDD Department of DefenseDHD down-hole drillingdischarge Water that moves from one area into

another.discontinuous permafrost A zone where

permafrost will be thin and maybe absent onthe south slopes of hills, in valley bottomscontaining permeable alluvial material, andunder surfaces that have been cleared ofvegetation. See also continuous permafrost;permafrost

dispersion treatment Adding dispersing agents todrilling fluid, backwashing, jetting water, orwater standing in the well to counteract thetendency of mud to stick to sand grains.

dissolution potential The possibility ofdeveloping high secondary permeability in asoluble rock because the rock dissolves throughcontact with groundwater.

DMA Defense Mapping AgencyDOD Department of Defensedolomite A carbonate rock that dissolves when

carbon dioxide from the atmosphere andgroundwater mix to form carbonic acid.

double-casing placement A method of placinggravel using a temporary outer casing.

drainage basin An area drained by a stream orriver. See also hydrographic basin (localdrainage basin); major river basin; regionalriver basin

drawdown Measure of how much the water levelnear the well is lowered when the well ispumped.

draw works Main drill-head hoists that aremechanically or hydraulically driven wire-linewinches,

drilling blind A condition that exists when adriller continues to drill when fluid circulation islost,

drive clamp Uused in driving easing or pipe and isattached to the square of the drill stem.

drive head Device that is placed on the pipe toprotect the threads the the driving blows of thedrive clamps; a drive head is put on byunscrewing the bit, slipping the drive head overthe drilling stem, and making up the joint again.

drive monkey A weight that slides over the pipeand is used in the falling-weight method ofdriving a well.

driven method Installing casing as with theborehole, the cable-tool, or driven-point wellmethod.

drive point Perforated pipe with a steel point atthe lower end to breakthrough pebbles or thin,hard layers.

drive shoe Device attached to the lower end of thepipe to prevent the pipe from crumpling whilebeing driven; a drive shoe is threaded to fit thepipe or casing.

dump-bailer method Placing grout in a casingusing a dump-bailer machine.

EAC echelons above corpselectric-line method A procedure to measure the

water level using an M-Scope. See alsoM-Scope

electrode selector switch A five-position switchlocated directly above the ohmmeter on theelectrical logging system.

Glossary-3

FM 5-484/NAVFAC P-1065/AFMAN 32-1072

elev elevationelevator (casing) A device used to handle pipe;

the elevator is clamped around the pipe directlyunder the coupling. See also pin hook; sandline

ENGR engineerevaporation Direct radiation from the sun that

causes liquid at the surface of a body of water tochange from a liquid to a vapor.

evaporite Sedimentary rock that is generallycapable of storing and transmitting groundwaterbut teds to dissolve in the water

E-Z Mud A synthetic, inorganic polymer.

F Fahrenheitfall-in Material that accumulates in the bottom of

the borehole after circulation stops,falling weight Driving method that uses a steel

driving bar attached to a rope; the bar fallsfreely inside the pipe and strikes the base of thedrive point.

feed drive Mechanism on a rotary rig that appliesa downward thrust to the drill string.

fibratex Commercial chemical agent added tomud drilling fluid to prevent it from freezing.See also aquagel; barite; gel-flake;irnpermex; micatex; smentex

filter cake Solids from the drilling mud depositedon the borehole wall as the water phase is lostinto the formation

fish Portion of the drill string left in the borehole.See also fishing; string failure

fishing An attempt to retrieve the portion of thedrill string left in the borehole. See also fishstring failure

flow-meter method A procedure used to measureflow rate using a turbine-type flow meter.

FM field manualFMF Fleet Marine Forcefoamer Substance used in air rotary drilling to

enhance the air’s ability to carry cuttings andreduce the velocity required to clean theborehole.

foot piece A device at the end of an air pipe thatbreaks the air into small streams so that thebubbles formed will be as small as possible.

formation stabilizer Material placed on theoutside of the screen to help preventdeterioration of the annular space; usingformation stabilizer is an alternative method tousing gravel-pack material.

fpm foot (feet) per minuteft foot (feet)ft/min foot (feet) per minutefunction switch A three-position selector switch

located directly beneath the galvanometers on theelectrical logging system.

gal gallon(s)galvanometers A zero-centered micrometer on the

electrical logging system.gel-flake Commercial chemical agent added to

mud drilling fluid to prevent it from freezing.See also aqualgel; barite; fibratex;impermex; micatex; smentex

gel strength Thickness of drilling mud at rest.geologic structure Feature, such as a fold,

fracture, joint, or fault, that disrupts thecontinuity of rock units.

geyser effect A result of denser mud in theanuular space flowing down the hole andforcing the clean drilling mud up the drill rods.

going crooked deviated boreholeGPH gallon(s) per hourGPM gallon(s) per minutegravel pack Artificial sand filter.gravity-outflow method A backwashing method

that involves pouring water into the well rapidlyto produce outflow through the screen openings.

groundwater indicators Features that suggest thepresence of groundwater.

hand auger A device that consists of a shaft orpipe with a wooden handle at the top and a bitwith curved blades at the bottom; a hand auger

Glossary-4

FM 5-484/NAVFAC P-1065/AFMAN 32-1072

can penetrate clay, silt, and those sands in whichan open borehole will stand without caving.

helical-rotor pump A positive-displacement,rotary-screw- or progressing-cavity-type pumpdesigned for relatively low-capacity, high-liftwells that arc 4 inches or larger in diameter.

HQ headquartershydraulic conductivity A measurement of the

relative flow of water through a subsurfacematerial; the results of the measurement arerelated to the size and spacing of particles orgrains in soils or to the number and size offractures in rocks.

hydrographic basin (local drainage basin)Subdivision of a regional river basin. See alsodrainage basin; major river basin; regionalriver basin

hydraulic gradient Determines the direction ofgroundwater flow.

hydrologic cycle The constant movement of waterabove, on, and below the earth’s surface.

ID inside diameterigneous rock Rock that forms when hot molten

material (magma) cools or solidifies eitherinside the earth’s crust or on the earth’s surface(lava). See also lava; magma

impermeable barriers Features (solid rockmasses) through which groundwater cannotflow.

impermex Commerical chemical agent added tomud drilling fluid to prevent it from freezing.See also aquagel; barite; fibratex; gel-flake;micatex; smentex

in inch(es)infiltration Precipitation on land surfaces that

seeps into the groundinside-tremie method Placing grout in the bottom

of the hole through a tremie pipe that is setinside the casing.

ISO International Standards OrganizationITWD InternationaI Standards Organization/

air-transportable water drill.

JCS Joint Chiefs of Staffjet-drive drilling A method of constructing small

wells in cold climates; the wells are usually 2inches in diameter and are drilled to a depth of200 feet.

jet pump A combination of a surface centrifugalpump, a down-hole nozzle and a venturiarrangement used in small diameter wellsrequiring a lift of 100 feet or less.

jetted well A well that is dug using a highvelocity stream of water.

jetting method A backwashing method thatinvolves using a jetting tool to remove cakeddrilling mud from the borehole wall; thismethod requires a large water supply.

JOG Joint Operations Graphics

karst topography Results from the dissolution ofcarbonate rocks by groundwater and ischaracterized by caves, sinkholes, closeddepressions, and disappearing streams.

kg kilogram(s)kg/m kilogram(s) per meterkv kilovolt(s)kw kilowatt(s)

lag time The time it takes sample material toreach the surface during a depth-determinationteat.

lava Magma that cools or solidifies on the earth’ssurface. See also igneous rock; magma

lb pound(s)lb/ft pound(s) per footlimestone A carbonate rock that dissolves when

carbon dioxide from the atmosphere andgroundwater mix to form carbonic acid.

lithification The process by which sediments areconverted to rock; lithifiiation includescompaction, consolidation, cementation anddesiccation.

LOG (logging) Position on the function switch onthe electrical logging system.

Glossary-5

FM 5-484/NAVFAC P-1065/AFMAN 32-1072

logging cable A cable on the electrical loggingsystem used to lower the probe into the welI.

loss zone Area where grout is lost into theformation.

lost circulation Volume loss of the drilling fluidreturning to the surface.

LPM liter(s) per minuteLVS Service Logistical Vehicle Systemsm meter(s)ma milliampere(s)magma Hot molten material. See also igneous

rock; lavamajor river basin Largest member in the river

basin grouping; the Mississippi River Basin is amajor river basin. See also drainage basin;hydrographic basin; regional river basin

Marsh funnel Device used to test mud viscosity;the funnel is 12 inches long and 6 inches indiameter, and it has a No 12 mesh strainer, a1,500-ml cone, a 2-inch-long calibrated hard-rubber orifice (inside diameter of 3/16 inch),and a 1,000-ml capacity cup.

Marsh-funnel test Procedure routinely conductedto determine the thickness or apparent viscosityof drilling fluid.

MEAPO Middle East/Africa Project Officemeasured-container method A procedure used

to determine flow rate from a well or pump bymeasuring the time required to fill a containerwith a known volume.

MEDEVAC medical evacuationmetamorphic rock Igneous, sedimentary, or

preexisting metamorphic rock that undergoesfurther transformation by changes in pressure,temperature or chemistry.

micatex Commerical chemical agent added tomud drilling fluid to prevent it from freezing.See also aquagel, barite; fibratex; gel-flake;impermex; smentex

min minute(s)ml milliliter(s)mm millimeter(s)MO Missouri

monitoring well Small water well used formeasuring water level, estimating well yield,and taking samples for quality analysis;monitoring wells are drilled next to permanentwells at specified intervals.

mph mile(s) per hourMS MississippiM-Scope Two-conductor, battery-powered

indicator used to measure water levels.mud pump A positive-displacemenc double-

acting piston pump with capacities ranging fromone to several hundred GPM at pressures up toseveral hundred psi.

mud rotary drilling A well-drilling method thatuses mud to circulate the drilling fluid duringthe drilling process.

N noN/A not applicableNATO North Atlantic Treaty organizationNAVFAC Naval Facilities Engineering CommandNBC nuclear, biological chemicalNCF naval construction forceNCOIC noncommissioned officer m chargeNMCB naval mobile construction battalionNo numberNSN national stock number

OD outside diameterohmmeter An instrument on the electrical logging

system that is located directly above the CALADJUST; the ohmmeter indicates the earthresistivity in ohm-feet.

open-hole method of installing casing Installingcasing into a borehole one casing section at atime.

open-hole method of installing screen Installingtelescoping screen when the depth and thicknessof the aquifer have been predetermined.

open-hole placement A method of installinggravel-pack material m a well.

Glossary-6

FM 5-484/NAVFAC P-1065/AFMAN 32-1072

open-pipe method A procedure to measuredischarge rates using a fully open pipe andmeasuring the distance the water stream travelsparallel to the pipe at a 12-inch vertical drop.

open-well method A compressed-air method thatinvolves establishing the surging cycle bypumping from the well with an air lift and bydropping the air pipe suddenly to cutoff thepumping action.

outside-tremie method Placing grout outside thecasing using a tremie pipe; this method is notrecommended for depths greater than 100 feet.

P pamphletparticle slip Downward movement of an object

through fluid.pendulum effect Action of creating a straight

borehole from a weighted drill string and bit.perched aquifer An aquifer that lies above an

unconfined aquifer and is separated from thesurrounding groundwater table by a confininglayer.

percussion drilling A method of drilling thatinvolves crushing by impact from the teeth ofthe drill bit percussion drilling for water wellsuses down-hole, pneumatic-percussion hammerdrills.

permafrost Permanently frozen rock and soil thatis widespread in the Arctic north of 50°Nlatitude; permafrost is either continuous ordiscontinuous. See also continuouspermafrost; discontinuous permafrost

permeability The capacity of a porous rock orsoil to transmit a fluid.

pH Negative logarithm of the effectivehydrogen-ion concentration or hydrogen-ionactivity in gram equivalents per liter used inexpressing acidity and alkalinity on a scale of Oto 14 with 7 representing neutrality.

pin hook Device used with an elevator to lift veryheavy strings of pipe; the hook is attached to therope socket on the drilling line. See alsoelevator (casing); sand line

pipe clamp A device used to hold the pipe at anyposition in the hole during drilling operations.

pipe tong Device used to tighten 6- and 8-inchdrive pipe.

pitcher pump A surface-mounted, reciprocatingor single-acting piston pump.

pitting A condition on bits that is caused by thepresence of foreign material such as rock cuttingor the use of rock drill oil with a high sulphurcontent.

playas Dry lake beds comprised mainly of clayand located in intermountain valleys.

POL petroleum, oils, and lubricantspolymer A water-based, organic, inorganic,

natural, synthetic, or synthetically formulatedadditive; polymers are formulated for variousdrilling fluid purposes and can be used alone orto enhance clay muds.

Poly-Sal Synthetic, inorganic polymer. See alsopolymer

popping A condition whereby a carbide insertwill pop clean from its socket if the drill stringis not properly fed up in the hole.

population distribution Surface indicator thatcould indicate water availability because ofpopulation density.

porosity Voids in soil and rocks.POT (potentiometer) A black plug receptacle

used to connect the surface-potential groundwire to the instrument.

power auger A device that is rotated, raised, andlowered by a power-driven mechanism; a powerauger has a depth limit of about 10 feet and canbe used only in areas where the water table isclose to the surface.

ppm parts per millionprecipitation Moisture released from clouds to

the earth in the form of rain, sleet, hail, or snow.pressure-pumping method A backwashing

method that involves capping the casing andpumping water into the well under pressure.

probe selector switch A switch on the electricallogging system that is located directly below theSP shutoff switch on units modified for mudlogging.

psi pound(s) per square inchpsig pound(s) per square inch gauge

Glossary-7

FM 5-484/NAVFAC P-1065/AFMAN 32-1072

PTO power takeoffpull-back method A way of installing telescoping

screen.pulldown. See feed drive

pump-surge method A backwashing method thatinvolves alternately pumping water to thesurface and letting water run back into the wellthrough the pump-column pipe.

push-tube A method of collecting undisturbedsoil samples; this method uses thin-wall,freed-piston samplers in very soft to stiff clays,silts, and sands that do not contain appreciableamounts of gravel.

PVC polyvinyl chloride

qanat A man-made, gently inclined undergroundchannel that allows groundwater to flow fromalluvial gravels at the base of hills to a drylowland; qanats appear as a series ofant-mound-like openings that run in a straightline and act as air shafts for a channel.

qt quart(s)Quick-Gel Wyoming-type bentonite drilling fluid

used for mixing mud

recharge Water that infiltrates the soil.recharge area Area where the groundwater

reservoir is replenished.RED HORSE rapid engineer deployable, heavy

operational repair squadron.regional river basin Subdivision of a major river

basin; the Missouri River Basin is a regionalriver basin of the Mississippi River Basin. Seealso drainage basin, hydrographic basin;major river basin

reservoir indicators Characteristics in soils,rocks, and landforms that define the ability of anarea to store and transmit groundwater butwhich do not directly indicate the presence ofgroundwater.

Revert A natural, organic polymer fluid derivedfrom the guar plant. See also polymer

RH-1 An air-transportable RED HORSE echeloncomposed of 16 people and ready fordeployment 12 hours after notification.

RH-2 An air-transportable RED HORSE echeloncomposed of 93 people and ready fordeployment 48 hours after notification.

RH-3 A RED HORSE echelon composed of 295people and ready for deployment six days afternotification

ringing off Fatigue failure in the drill-rod jointscaused by excessive torque or thrust or byborehole deviation.

riparian vegetation Dense strands of vegetationalong stream channels.

rivers. See streams and riversrock development A well-development method

used in rock formations that involves combiningjetting with air-lift pumping to wash out finecuttings, silt, and clay.

rotary pump A pump that uses a system ofrotating gears to create a suction at the inlet andforce a water stream out of the discharge.

rotary table Rotating platform on a rotary rig thattransmits torque to the drill rod through thekelly.

ROWPU reverse osmosis water purification unitsRPM revolution(s) per minuterung off See string failurerunoff Precipitation on land surfaces that flows

along the surface.

S3 Operations and Training Officer (US Army)sacrificial anode A simple method of protecting

metal casing from corrosion by connecting agalvanically active metal bar to the casing.

salt encrustation Surface indicator that oftenoccurs in playas and is indicative of salinegroundwater.

saltwater encroachment Movement of saltwaterinto zones previously occupied by freshwater.

saltwater intrusion Invasion of salt water intofreshwater during pumping.

sanded in A condition that exists when the stringbecomes stuck when cuttings collect on the bitand collar shoulder.

Glossary-8

FM 5-484/NAVFAC P-1065/AFMAN 32-1072

sand line Device used with the elevator for liftingone or two half lengths of pipe. See alsoelevator (casing); pin hook

sandstone Consolidated or cemented sand.saturated thickness Distance between the top of

the groundwater and the bottom of the aquifer.SC supply catalogSCFM sea level cubic foot (feet) per minutesemipermeable barriers Features (faults or

fractured rock masses) that restrict flow but donot act as a complete barrier.

sedimentary rock Rocks that are composed ofsediments that are converted to rock throughcompaction cementation or crystallization.

self-jetting method Digging a jetted well bysinking a continuous-slot-, brass-jacket-, orjet-head-tapering-type well point.

self-potential potentiometer The instrument inthe electrical logging system that balances outthe SP that exists between any pair of potentialelectrodes.

self-priming pump A pump with a primingchamber that makes repriming unnecessarywhen the pump is stopped for any reason otherthan au intentional draining.

semipermeable barriers Features (faults orfractured rock masses) that restrict water flowbut do not act as complete barriers.

shale Fine-grained sedimentary rock that does notstore much groundwater and does not transmitlarge quantities of groundwater.

single-string method of installing casingInstalling casing and screen (already joined) in asingle assembly.

single-string method of installing screen. Seesingle-string method of installing casing

sinker rod An insulated device that can beattached with a leather thong to the probe on theelectrical logging system if more weight isneeded to carry the probe to the bottom of a well.

smentex Commercial chemical agent added tomud drilling fluid to prevent it from freezing.See also aquagel; barite; fibratex; gel-flake;impermex; micatex

snow-melt pattern Surface indicator that canprovide evidence of recharge areas anddirections of groundwater flow.

soil moisture Surface indicator that can providesome indication of recharge and discharge areas;soil moisture content is related to local rainfalland to grain size.

SOP standing operating proceduresSP spontaneous potentialspecific retention Water that cannot be pumped

out of a well.specific yield Water that can be pumped from a

well.spring Effluence of groundwater occurring where

the water table intercepts the ground surface; aspring is a good surface indicator of thepresence of shallow groundwater occurrences.

SP polarity-reversing switch A switch on theelectrical logging system that is located directlybelow the SP potentiometer the switch showsthe polarity of the particular cable electrodebeing used.

SP shutoff switch A spring-return switch on theelectrical logging system that is located in theupper left comer of the panel; this switchautomatically shuts off the l-1/2-volt C-batterywhen the instrument lid is closed.

spudding Raising or lowering the drill string.spudding in Starting the borehole.squeezing See swelling soilSr specific retentionstabilizers Items, such as drill collars, used on the

drill string during drilling operations.STANAG Standardization AgreementSTD standardSTP Soldier Training Publicationstraight pumping A well-completion method that

uses a pitcher-spout hand pump.

Glossary-9

FM 5-484/NAVFAC P-1065/AFMAN 32-1072

streams and rivers Surface indicators that areusually recharge areas in arid regions and maybe recharge or discharge areas in temperateclimates; areas adjacent to streams areconsidered good locations for wells but are notalways the best available areas for water wellsbecause of soil content.

string failure A condition that exists when thedrill string parts, leaving a portion in theborehole the drill string is rung off. See alsofish; fishing

submergence The proportion (percentage) of thelength of the air pipe that is submerged belowthe pumping level.

submersible pump A centrifugal pump closelycoupled with an electric motor that can beoperated underwater,

submersible-pump method A pump-testingmethod that uses a submersible pump to pumptest the water well.

surface indicator Feature that suggests thepresence of groundwater.

surface-water divide Boundary betweengroundwater flow systems.

surge-block method A backwashing method thatinvolves developing a well by surging water upand down the casing with a surge block orplunger.

swelling soil (squeezing) In-hole effects of shaleor clay that absorb water from the drilling fluid

Sy specific yield

TAC Terrain Analysis CenterTAD Transatlantic Divisiontag-along compressor auxiliary compressortape method Procedure to measure the depth to

the static level in a shallow well.TEC united states Army corps of Engineers

Topographic Engineering CenterTM technical manualTN TennesseeTO technical manualTO theater of operations

TOA table of allowancestop head A mechanism on a rotary rig that moves

down along the rig mast as the boring isadvanced and is raised to the top of the mast toadd a length of drill pipe; the top-head driveuses a power swivel.

TRADOC United States Army Training andDoctrine Command

transmissivity The product of hydraulicconductivity and the saturated thicknessexpressed in gallons per day per foot of aquiferwidth.

transpiration Water that Wrens to theatmosphere from plants.

tremie placement Placing gravel-pack materialusing a tremie pipe.

tricone bit A bit that consists of three con-shaped rollers with steel teeth milled into thesurfaces.

turbine pump A shaft-driven, multistage,centrifugal pump containing several impellers orbowl assemblies.

uncased-interval method Installing casing inwells located in rock formations.

unconfined aquifer An aquifer that is partly filledwith water, has fluctuating water levels, and canreceive direct recharge from percolating surfacewater.

unconsolidated deposit Consists of weatheredrock particles of varying materials end sizes.

unscreened well A well in competent rock thatdoes not require a screen; the aquifer is tappedthrough numerous, irregularly spaced fractures.

US United States (of America)USAF United States Air ForceUSGS United States Geological Survey

vegetation type Surface indicator that can helpdefine the location of recharge and dischargeareas end groundwater.

viscosity Relates to true (Newtonian) fluids suchas water; viscosity is a proportional constantbetween sheer stress and rate in laminar flow.

Glossary-10

FM 5-484/NAWAC P-1065/AFMAN 32-1072

wall stuck A condition that exists when thealignment of a fine-grained soil or shale holedeviates significantly and the drill pipe wallowsinto the wall.

washdown method Installing screen in an aquiferthat is composed of fine to coarse sand withlittle or no gravel.

wash-in method Installing casing by advancingthe borehole for an expedient jetted-wellconstruction.

water-table wells Wells drilled into anunconfined aquifer.

WDRT Water Detection Response TeamWDS well-drilling systemwell probe A device on the electrical logging

system that consists of one brass currentelectrode and three lead-oxide potentialelectrodes.

WES United States Army Corps of EngineersWaterways Experirment Station

wetlands Marshes, bogs, and swamps that arcindicative of very shallow groundwater.

WRDB Water Resources Data Base

XS extra strength

Y yesyield Volume of water discharged from a well per

unit of time when water is being pumped or isflowing freely.

yield point Mud quality broadly included mviscosity.

Glossary-11

FM 5-484/NAVFAC P-1065/AFMAN 32-1072

References

SOURCES USED

These are the sources quoted or paraphrased in this publication.

International Standardization Agreement

STANAG 2885 ENGR (Edition 2). Emergency Supply of Water in War. 9 November 1990.

Military Publications

FM 5-33. Terrain Analysis. 11 July 1990.

FM 5-34. Engineer Field Data. 14 September 1987.

FM 5-116. Engineer Operations Echelons Above Corps. 7 March 1989.

TM 5-725. Rigging. 3 October 1968.

Nonmilitary Publications

Baroid Properties and Performance of Drilling Muds. Baroid Drilling Fluids, Inc. Houston, Texas.Catalog no. WW 1000-01. 1989

Geology and Geophysics for Military Well Drillers. Geotechnical Laboratory, US Army EngineersWaterways Experiment Station. Vicksburg, Mississippi.

Groundwater Atlas of the United States: Hydrologic Investigations Atlas. Department of theInterior USGS. Denver, Colorado.

Chapter 730-A. Introductory material and nationwide summaries (Segment no. 0).Chapter 730-B. California, Nevada (Segment no. 1).Chapter 730-C. Arizona, Colorado, New Mexico, Utah (Segment no. 2).Chapter 730-D. Kansas, Missouri, Nebraska (Segment no. 3).Chapter 730-E. Oklahoma, Texas (Segment no. 4).Chapter 730-F. Arkansas, Louisiana, Mississippi (Segment no. 5).Chapter 730-G. Alabama, Florida, Georgia, South Carolina (Segment no. 6).Chapter 730-H. Idaho, Oregon, Washington (Segment no. 7).Chapter 730-1. Montana, North Dakota, South Dakota, Wyoming (Segment no. 8).Chapter 730-J. Iowa, Michigan, Minnesota, Wisconsin (Segment no. 9).Chapter 730-K. Illinois, Indiana, Kentucky, Ohio, Tennessee (Segment no. 10).Chapter 730-L. Delaware, Maryland, New Jersey, North Carolina, Pennsylvania, Virginia, West

References-1

FM 5-484/NAVFAC P-l065/AFMAN 32-1072

Virginia (Segment no, 11),Chapter 730-M. Connecticut, Maine, Massachusetts, New Hampshire, New York, Rhode Island,

Vermont (Segment no, 12).Chapter 730-N. Alaska, Hawaii, Puerto Rico (Segment no. 13).

Ground Water and Wells. Third Edition. Johnson Filtration Systems, Inc. St. Paul, Minnesota.ISBN 0961645601, 1989.

Percusion Drilling Equipment Operation and Maintenance Manual. (Catalog no. M500-2.)Mission Drilling Products Division, TRW Energy Products Group. Houston, Texas

Techniques of Water-Resources Investigations of the United States Geological Survey.Applications of Borehole Geophysics to Water-Resources Investigations. Book no. 2. USGeological Survey. Arlington, Virginia.

The Button Bit vs The Rock. (Publication Form no. 769-l.) Ingersoll-Rand Company. Roanoke,Virginia.

Water Well Manual. U.C. Gibson and R.D. Singer. Premier Press, California. 1971.

DOCUMENTS NEEDED

These documents must be available to the users of this publication.

DD Form 2678. Well Driller’s Log. October 1993.

DD Form 2679. Piping and Casing Log. October 1993.

DD Form 2680, Military Water Well Completion Summary Report. October 1993.

DA Form 2028. Recommended Changes to Publications and Blank Forms, February 1974.

DOD Defense Mapping Agency Catalog of Maps, Charts, and Related Products, Part 3 V.

FM 5-250. Explosives and Demolitions. 15 June 1992.

FM 5-410. Military Soils Engineering. 23 December 1992.

TM 5-545. Geology. 8 July 1971.

TM 5-818-5, Dewatering and Groundwater Control. 15 November 1983 w/change 1, June 1985.

TM 5-3820-256-10. Operating and Maintenance Instructions for Drilling System, Well Rotary,Truck Mounted, Air Transportable, 600 Feet Capacity, Model Number LP-12. 15 March 1989w/change 1, 1 September 1990.

STP 5-62J12-SM-TG. Soldier’s Manual and Trainer’s Guide, MOS 62J. General ConstructionEquipment Operator, Skill Levels 1/2. 15 October 1986.

STP 5-62N34-SM-TG. Construction Equipment Supervisor Soldier’s Manual and Trainer’sGuide. MOS 62N, Skill Levels 3/4. 21 February 1989.

References-2

FM 5-484/NAVFAC P-1065/AFMAN 32-1072

SC 3820-97-CL-E01. Pneumatic Tool and Compressor Outfit, 250 CFM; Truck Mounted.14 June 1974

AFI 10-209. Civil Engineering RED HORSE Squadron. April 1983

API 91-202. US Air Force Mishap Prevention Program. March 1987.

AFT 91-301. Air Force Occupational Safety Fire Prevention and Health Program. May 1990.

TO lC-130A-9. Cargo Loading Manual. 16 June 1980 w/changes 1 through 8, 5 December 1988.

A1OO-66. American WaterBaltimore. 1925

Military Publications

Works Association Standard for Deep Wells. Waverly Press,

READINGS RECOMMENDED

AR 600-200. Enlisted Personnel Management System. 15 September 1990.

AR 735-5. Policies and Procedures for Property Accountability. 31 January 1992.

AR 750-1. Army Materiel Maintenance Policy and Retail Maintenance Operations.27 September 1991.

FM 5-33. Terrain Analysis. 11 July 1990 w/change 1, September 1992.

FM 5-100. Engineer Combat Operations. 22 November 1988.

FM 5-104. General Engineering. 12 November 1986.

FM 5-233. Construction Surveying. 4 January 1985.

FM 5-333. Construction Management. 17 February 1987 w/ change 1, April 1991.

FM 5-335. Drainage. 2 December 1985.

FM 5-434. Earthmoving Operations. 30 September 1992.

FM 22-100. Military Leadership. 31 July 1990.

FM 25-101. Battle Focused Training. 30 September 1990

FM 5-430-00-l/AFP 93-4, Vol I. Planning and Design of Roads, Airfields, and Heliports in theTheater of Operations (Road Design). To be published withing 6 months.

FM 5-430-00-2/AFP 93-4, Vol II. Planning and Design of Roads, Airfields, and Heliports in theTheater of Operations (Airfield Design). To be published withing 6 months.

ARTEP 5-500. Engineer Cellular Teams. 30 July 1980.

Nonmilitary Publications

Applications of Electrical Logging to Water Well Problems. F. L. Bryan. Water Well Journal, 4:1,1950.

References-3

FM 5-484/NAVFAC P-1065/AFMAN 32-1072

Application of Electrical and Radioactive Well Logging to Ground-Water Hydrology. E. P. Pattenand G. D. Bennett. US Geological Survey Water Supply Paper 1544 D. 1963.

Electric Logging Applied to Groundwater Exploration. P. H. Jones and T. B. Buford. Geophysics,16:1. January 1951.

Electrical Well Logging. H. Guyed. The Oil Weekly, a series of articles published from August 7to December 4, 1944.

Interpretation of Electric and Gamma Ray Logs in Water Wells. H. Guyed. American GeophysicsUnion. Technical Paper. Mandrel Industries Inc. Houston, Texas. 1965.

Investigation of Ground Water Supplies with Electrical Well Logs. H. Guyed. Water Well Journal.May 1957.

Investigation of Groundwater Supplies with Electric Well Logs. T. S. Morris. Water Well Journal.May-June 1952.

The Quantitative Aspects of Electric Lag Interpretation. J. E. Walstrom. Trans. Am. Inst. Min. andMet. Engrs., Vol 195. 1952.

Well Drilling Manual. National Water Well. Dublin, Ohio. ISBN 0-318-15937-6

Well Drilling Operations. National Water Well. Dublin, Ohio. ISBN 0-318-23051-8

Well Site Geologists Handbook. Donald McPhater. Tulsa, Oklahoma. ISBN 0-87814-217

References-4

FM 5-484/NAVFAC P-1065/AFMAN 32-1072

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Index-11

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FM 5-484NAVFAC P-1065AFMAN 32-1072

8 MARCH 1994

By Order of the Secretaries of the Army, the Navy, and the Air Force:

Official:

GORDON R. SULLIVANGeneral, United States Army

Chief of Staff

MILTON H. HAMILTONAdministrative Assistant to the

Secretary of the Army06076

O f f i c i a l :

JOHN H. DALTONSecretary of the Navy

O f f i c i a l :

MERRILL A. McPEAKGeneral, United States Air Force

Chief of Staff

RONALD W. YATESGeneral, United States Air Force

Commander, Air Force Materiel Command

DISTRIBUTION :

Active Army, USAR, and ARNG: To be distributed in accordance withDA Form 12-llE, requirements for FM 5-484, Multiservice Proceduresfor Well-Drilling Operations (Qty rqr block no. 0756).

✩ U.S. GOVERNMEBT PRINTING OFFICE: 1994-528-027/80127

PIN: 072131-000